Method, rated voltage adjusting device, and electric storage device

ABSTRACT

An electric storage system to which a first electric storage device and a second electric storage device connected in parallel can be mounted decides a rated voltage of the first electric storage device in an electric storage system having at least one of (A) a discharge standby stage and (B) a charge standby stage. It decides a large and small relationship between the rated voltage of the electric storage device for which at least one of (i) an accumulated time, (ii) an accumulated power amount, and (iii) an accumulated number is decided to be made higher among the first electric storage device and the second electric storage device, and the rated voltage of the other electric storage device. It decides the rated voltage of the first electric storage device such that the large and small relationship decided in the large and small relationship deciding step is achieved.

The contents of the following Japanese patent application areincorporated herein by reference:

NO. 2020-151672 filed in JP on Sep. 9, 2020.

BACKGROUND 1. Technical Field of State

The present invention relates to a method, a rated voltage adjustingdevice, and an electric storage device.

2. Related Art

In an electric storage system including a plurality of electric storagemodules, the electric storage modules may be connected in parallel insome cases (for example, see Patent Document 1). Patent document 2discloses an electric storage system that enables hot-swapping electricstorage modules.

PRIOR ART DOCUMENT Patent Document

[Patent Document 1] Japanese Patent Application Publication No.H11-98708

[Patent Document 2] International Publication WO 2017/086349

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an example of a system configuration of theelectric storage system 100.

FIG. 2 schematically shows an example of a system configuration of theelectric storage module 110.

FIG. 3 schematically shows an example of a system configuration of themodule control unit 240.

FIG. 4 schematically shows an example of a system configuration of thesystem control unit 140.

FIG. 5 schematically shows an example of a circuit configuration of theelectric storage module 110.

FIG. 6 schematically shows an example of a system configuration of aswitching unit 630.

FIG. 7 schematically shows an example of a system configuration of anelectric storage module 710.

FIG. 8 schematically shows an example of a system configuration of aswitching unit 730.

FIG. 9 schematically shows an example of a system configuration of anelectric storage system 900.

FIG. 10 schematically shows an example of a system configuration of anelectric storage module 1010.

FIG. 11 schematically shows an example of a system configuration of amodule control unit 1040.

FIG. 12 schematically shows an example of a circuit configuration of themodule control unit 1040.

FIG. 13 schematically shows an example of a circuit configuration of themodule control unit 1040.

FIG. 14 schematically shows an example of a system configuration of anelectric storage module 1410.

FIG. 15 schematically shows an example of a system configuration of acircuit configuration of a voltage adjusting unit 1430.

FIG. 16 schematically shows an example of the voltage adjusting unit1430.

FIG. 17 schematically shows an example of a system configuration of anelectric storage module 1710.

FIG. 18 schematically shows an example of a discharge standby stage ofthe electric storage system 100.

FIG. 19 schematically shows an example of a charge and dischargecharacteristic of the electric storage module.

FIG. 20 schematically shows an example of the variation in the currentvalue of discharge current of the electric storage module.

FIG. 21 schematically shows an example of the charge and dischargecharacteristic of the electric storage module.

FIG. 22 schematically shows an example of the variation in the currentvalue of the discharge current of the electric storage module.

FIG. 23 schematically shows an example of a method for deciding therated voltage of the electric storage module.

FIG. 24 schematically shows an example of a charge standby stage of theelectric storage system 100.

FIG. 25 schematically shows an example of the variation in the currentvalue of the charge current of the electric storage module.

FIG. 26 schematically shows an example of the variation in the currentvalue of the charge current of the electric storage module.

FIG. 27 schematically shows an example of an internal configuration ofthe electric storage unit 2710.

FIG. 28 schematically shows another example of the module control unit240.

FIG. 29 schematically shows another example of the system control unit140.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, (some) embodiment(s) of the present invention will bedescribed. The embodiment(s) do(es) not limit the invention according tothe claims, and all the combinations of the features described in theembodiment(s) are not necessarily essential to means provided by aspectsof the invention. Also, the embodiment(s) will be described withreference to the drawings. The identical or similar parts in thedrawings may be given the same reference numerals to omit thedescription that could otherwise overlap.

FIG. 1 schematically shows an example of the system configuration of anelectric storage system 100. In an embodiment, the electric storagesystem 100 is electrically connected to a load device 12 and suppliespower to the load device 12 (in some cases, this is referred to asdischarge from the electric storage system 100). In another embodiment,the electric storage system 100 is electrically connected to a chargingdevice 14 to accumulate electrical energy (in some cases, this isreferred to as charge of the electric storage system). The electricstorage system 100 may be used, for example, in electric storagedevices, electrical appliances, and transport equipment. Examples of thetransport equipment include electric vehicles, hybrid cars, electrictwo-wheeled vehicles, railway vehicles, airplanes, elevators, andcranes.

In the present embodiment, the electric storage system 100 includes aconnection terminal 102, a connection terminal 104, a wire 106electrically connecting the connection terminal 102 and the connectionterminal 104, an electric storage module 110 having a positive terminal112 and a negative terminal 114, an electric storage module 120 having apositive terminal 122 and a negative terminal 124, and a system controlunit 140. The electric storage module 110 and the electric storagemodule 120 may be examples of the electric storage devices configuredsuch that they can be connected in parallel. For example, the electricstorage module 110 may be an example of an electric storage device, andthe electric storage module 120 may be an example of a distinct electricstorage device. The electric storage device may be an example of a powersupply device. The system control unit 140 may be an example of abattery characteristic acquiring unit. The system control unit 140 maybe an example of an output unit.

The electric storage system 100 is electrically connected to the loaddevice 12 or the charging device 14 via the connection terminal 102 andthe connection terminal 104. In the present embodiment, the electricstorage module 110 and the electric storage module 120 are connected inparallel by a wire 106. Also, each of the electric storage module 110and the electric storage module 120 is held in a housing of the electricstorage system 100 in an attachable and detachable manner. Each of theelectric storage module 110 and the electric storage module 120 canthereby be replaced individually.

In the present embodiment, each of the electric storage module 110 andthe electric storage module 120 can switch the connection relationshipof its electric storage unit and the wire 106, based on a control signalfrom the system control unit 140 or the user operation. For example,each of the electric storage module 110 and the electric storage module120 can electrically connect its electric storage unit to the wire 106and electrically disconnect its electric storage unit from the wire 106based on a control signal from the system control unit 140 or the useroperation.

Each of the plurality of electric storage modules included in theelectric storage system 100 can thereby be individually replaced withoutconcerns about the damage or deterioration of the electric storagemodule even if the voltage of an electric storage module to be newlyimplemented in the electric storage system 100 and the voltage of theelectric storage module already implemented in electric storage system100 are different. The reasons for this are, for example, as describedbelow.

Owing to improvements in the performance of lithium-ion batteries inrecent years, the impedance of the lithium-ion battery has dropped toapproximately 10 mΩ. Because of this, for example, even if the voltagedifferential between two electric storage modules is only 0.4 V, a largecurrent as much as 40 A flows from the electric storage module having ahigher voltage toward an electric storage module having a lower voltagewhen the two electric storage modules are connected in parallel. As aresult, the electric storage module(s) deteriorate or are damaged. Notethat the voltage of the electric storage module may be the voltagebetween the positive terminal and the negative terminal of the electricstorage module (in some cases, the voltage is referred to as theterminal voltage of the electric storage module).

If one of the plurality of electric storage modules connected inparallel is individually replaced, in order to prevent the deteriorationor damage of the electric storage modules associated with replacing theelectric storage module, the voltage of the electric storage module tobe newly implemented and the voltage of the already implemented electricstorage module may be adjusted, prior to replacing the electric storagemodule, over some time until the voltage differential between theelectric storage modules becomes very small. By making the voltagedifferential between the electric storage module to be newly implementedand the already implemented electric storage module very small, a largecurrent can be prevented from flowing into each electric storage modulewhen the electric storage module is replaced. As a result, thedeterioration or damage of the electric storage modules can besuppressed. However, as the impedance of the lithium-ion batterydecreases, the tolerance of the voltage differential between theelectric storage module to be newly implemented and the alreadyimplemented electric storage module also decreases, so that it may takea great amount of time to adjust the voltage differential.

In contrast, according to the electric storage system 100 of the presentembodiment, each of the electric storage module 110 and the electricstorage module 120 can switch the connection relationship between itselectric storage unit and the wire 106, based on a control signal fromthe system control unit 140 or the user operation. Then, the electricstorage module 110 can be replaced, for example, in accordance with thefollowing procedure.

First, a user detaches an old electric storage module 110 from theelectric storage system 100. Then, the user performs operation forelectrically disconnecting the electric storage unit of a new electricstorage module 110 and the wire 106 before implementing the new electricstorage module 110 in the electric storage system 100. For example, theuser electrically disconnects the positive terminal 112 and the electricstorage unit by manually operating a switching element arranged betweenthe positive terminal 112 and the electric storage unit of the electricstorage module 110.

Subsequently, the user implements the electric storage module 110 in theelectric storage system 100, with the positive terminal 112 and theelectric storage unit electrically disconnected. Because the positiveterminal 112 and the electric storage unit are electrically disconnectedat this time, the current does not flow between the electric storagemodule 110 and the electric storage module 120 even if the voltagedifferential between the electric storage module 110 and the electricstorage module 120 is relatively large. Subsequently, when the voltagedifferential between the electric storage module 110 and the electricstorage module 120 has become an appropriate value, the system controlunit 140 executes the operation for electrically connecting the electricstorage module 110 and the wire 106. Note that the detail of the systemcontrol unit 140 will be described below.

As described above, according to the electric storage system 100 of thepresent embodiment, if an electric storage module is replaced orimplemented, it is not necessary to strictly adjust the voltage of theelectric storage module to be newly implemented in the electric storagesystem 100 and the voltage of the electric storage module alreadyimplemented in the electric storage system 100. Because of this, theelectric storage module can be easily and quickly replaced orimplemented.

The system control unit 140 controls each unit of the electric storagesystem 100. In an embodiment, the system control unit 140 decides thestate of the electric storage system 100. Examples of the states of theelectric storage system 100 include the state of charge, the state ofdischarge, the state of standby, or the state of stop.

For example, the system control unit 140 receives information related toa charge and discharge event and decides the state of the electricstorage system 100 based on the information related to the charge anddischarge event. Examples of the information related to the charge anddischarge event include: (i) a charge request or a discharge requestfrom an external apparatus such as the load device 12 and the chargingdevice 14; (ii) information indicating that an external apparatus hasbeen connected; (iii) information indicating the type of an externalapparatus; (iv) information indicating operation of an externalapparatus; (v) information indicating the state of an externalapparatus; (vi) information indicating a user instruction or operationwith respect to an external apparatus; (vii) information indicating auser instruction or operation with respect to the electric storagesystem 100; and (viii) the combination of the above.

For example, the system control unit 140 judges that the electricstorage system 100 is in the state of discharge if the system controlunit 140 has detected the connection of the load device 12 or received asignal indicating the type of the load device 12. The system controlunit 140 may also judge that the electric storage system 100 is in thestate of discharge upon receiving from the load device 12 a signalindicating that the power will be used. Examples of the signalsindicating that the power will be used include a signal indicating thata power supply of the load device 12 will be turned on, a signalindicating that the power supply of the load device 12 has been turnedon, a signal indicating that the load device 12 will be shifted to anoperation mode, and a signal indicating that the load device 12 hasshifted to the operation mode.

The system control unit 140 may judge that the electric storage system100 is in the state of charge if the system control unit 140 hasdetected the connection of the charging device 14 or received a signalindicating the type of the charging device 14. The system control unit140 may also judge that the electric storage system 100 is in the stateof charge upon receiving from the charging device 14 a signal indicatingthat charging will start. The system control unit 140 may also judgethat the electric storage system 100 is in the state of charge uponreceiving from the load device 12 a signal indicating that aregenerative current has occurred or that a regenerative current mayoccur.

In another embodiment, the system control unit 140 monitors the state ofeach of the electric storage module 110 and the electric storage module120. The system control unit 140 may collect information related to thebattery characteristic of the electric storage unit included in each ofthe electric storage module 110 and the electric storage module 120. Theinformation related to the battery characteristic of the electricstorage unit may be at least one selected from: the voltage value of theelectric storage unit; the current value of the current flowing throughthe electric storage unit; the battery capacity of the electric storageunit; the temperature of the electric storage unit; the deteriorationstate of the electric storage unit; and SOC (State Of Charge) of theelectric storage unit.

The information related to the battery characteristic (in some cases,referred to as the battery characteristic of an electric storage module)of the electric storage unit may include at least one of informationrelated to the specification of the electric storage unit andinformation related to the deterioration state of the electric storageunit. The battery characteristic of the electric storage unit may be abattery characteristic of one of a plurality of single batteriesconstituting the electric storage module or may be the batterycharacteristic of combination of the plurality of single batteries.Examples of the information related to the specification of the electricstorage unit include information related to: the type or model of theelectric storage unit; the connection state of the electric storageunit; the type of charging method that can charge the electric storageunit; the type of charging method that cannot charge the electricstorage unit; the rated battery capacity (in some cases, referred to asthe rated capacity); the rated voltage; the rated current; the energydensity; the maximum charge and discharge current; the chargecharacteristic; the charge temperature characteristic; the dischargecharacteristic; the discharge temperature characteristic; theself-discharge characteristic; the charge and discharge cyclecharacteristic; the equivalent series resistance in the initial state;the battery capacity in the initial state; the SOC [%] in the initialstate; and the electric storage voltage [V]. Examples of the chargingmethods include the CCCV charging method, the CC charging method, andthe trickle charging method.

Examples of the connection states of the electric storage unit includethe types, the number, and the connection forms of the unit cellsconstituting the electric storage unit. Examples of the connection formsof the unit cells include the number of the unit cells connected inseries and the number of the unit cells connected in parallel. Theenergy density may be a volume energy density [Wh/m³] or weight energydensity [Wh/kg].

Examples of the information related to the deterioration state of theelectric storage unit include information of the electric storage unittaken at an optional time, which include information related to: (i) thebattery capacity in the state of full charge; (ii) SOC in apredetermined temperature condition; (iii) SOH (State Of Health); (iv)equivalent series resistance (in some cases referred to as DCR orinternal resistance); and (v) at least one of the use time, the numberof charging, the charge amount, the discharge amount, the number ofcharge and discharge cycles, a thermal stress factor, and an overcurrentstress factor that have been integrated since the initial state or apredetermined timing. The information related to the batterycharacteristic of the electric storage unit may also associateinformation related to the deterioration state of the electric storageunit with information related to the time of day that the informationwas acquired, and store the associated information. The informationrelated to the battery characteristic of the electric storage unit maystore information related to the deterioration state of the electricstorage unit at a plurality of time of day.

SOH [%] is expressed, for example, as the full charge capacity in thedeterioration state (for example, the present full charge capacity)[Ah]÷the initial full charge capacity [Ah]×100. Although the calculationmethods or the estimation methods of SOH are not particularly limited,SOH of the electric storage unit is, for example, calculated orestimated based on at least one of the direct current resistance valueand the open circuit voltage value of the electric storage unit. SOH maybe a value in a predetermined temperature condition obtained fromconversion using an optional conversion formula or the like.

The methods of determining the deterioration state of the electricstorage unit are not particularly limited, and determination methodsthat are currently known or will be developed in the future may be used.In general, as the electric storage unit further deteriorates, theavailable battery capacity decreases while the equivalent seriesresistance increases. Because of this, for example, the deteriorationstate of a battery can be determined by comparing the present batterycapacity, SOC, or the equivalent series resistance, with the batterycapacity, SOC, or the equivalent series resistance of the initial state.

SOC [%] is expressed as, for example, the remaining capacity [Ah]÷thefull charge capacity [Ah]×100. Although the calculation methods or theestimation methods of SOC are not particularly limited, SOC is, forexample, calculated or estimated based on at least one of: (i) ameasurement result of the voltage of the electric storage unit; (ii) I-Vcharacteristic data of the voltage of the electric storage unit; and(iii) an integrated value of the current value of the electric storageunit. SOC may be a value in a predetermined temperature conditionobtained from conversion using an optional conversion formula or thelike.

The information related to the battery characteristic of the electricstorage unit may be information related to at least one of the chargetime and the discharge time of the electric storage unit. The chargetime and the discharge time of the electric storage unit mayrespectively be the charge time and the discharge time of the electricstorage module including the electric storage unit. In general, as theelectric storage unit further deteriorates, the available batterycapacity decreases and at least one of the charge time and the dischargetime shortens.

Information related to the charge time of the electric storage unit mayinclude information indicating the ratio of the charge time of theelectric storage unit to the charge time of the electric storage system100. The information related to the charge time of the electric storageunit may include information indicating the charge time of the electricstorage system 100 and information indicating the charge time of theelectric storage unit. The above described charge time may be: (i) timeduring which current or voltage has been applied to the electric storagesystem 100 or the electric storage unit in a single charging operation;or (ii) the sum of time during which current or voltage has been appliedto the electric storage system 100 or the electric storage unit in oneor more charging operations in a predetermined period.

The information related to the charge time of the electric storage unitmay include information indicating the ratio of the number of chargingof the electric storage unit in a predetermined period to the number ofcharging of the electric storage system 100 in the period. Theinformation related to the charge time of the electric storage unit mayinclude information indicating the number of charging of the electricstorage system 100 in a predetermined period and information indicatingthe number of charging of the electric storage unit in the period.

The information related to the discharge time of the electric storageunit may include information indicating the ratio of the discharge timeof the electric storage unit to the discharge time of the electricstorage system 100. The information related to the discharge time of theelectric storage unit may include the discharge time of the electricstorage system 100 and the discharge time of the electric storage unit.The above described discharge time may be: (i) time during which theelectric storage system 100 or the electric storage unit has suppliedcurrent or voltage in a single discharging operation; or (ii) the sum oftime during which the electric storage system 100 or the electricstorage unit has supplied current or voltage in one or more dischargingoperations in a predetermined period.

The information related to the discharge time of the electric storageunit may include information indicating the ratio of the number ofdischarging of the electric storage unit in a predetermined period tothe number of discharging of the electric storage system 100 in theperiod. The information related to the discharge time of the electricstorage unit may include the number of discharging of the electricstorage system 100 in a predetermined period and the number ofdischarging of the electric storage unit in the period.

The system control unit 140 may transmit to an external apparatus atleast one of the information related to the battery characteristic ofthe electric storage unit included in the electric storage module 110and the information related to the battery characteristic of theelectric storage unit included in the electric storage module 120. Theexternal apparatus can thereby use the information related to thebattery characteristic of an electric storage unit. Examples of theexternal apparatuses include the load device 12 and the charging device14. The external apparatus may be an output device that outputsinformation to a user. Examples of the output devices include a displaydevice and a voice output device such as a microphone. The output devicemay be an example of the output unit.

The system control unit 140 may determine the performance of theelectric storage module based on the information related to the batterycharacteristic of the electric storage module. The system control unit140 may also output information indicating that the performance of theelectric storage module is insufficient if the battery characteristic ofthe electric storage module does not satisfy a predetermineddetermination condition. The system control unit 140 may also decide thedetermination condition based on the application of the electric storagesystem 100.

As described above, in the present embodiment, the system control unit140 collects at least one of the information related to the batterycharacteristic of the electric storage unit included in the electricstorage module 110 and the information related to the batterycharacteristic of the electric storage unit included in the electricstorage module 120 and transmits the collected information to theexternal apparatus. However, the electric storage system 100 is notlimited to the present embodiment. In another embodiment, each of theelectric storage module 110 and the electric storage module 120 may alsocollect the information related to the battery characteristic of theelectric storage unit included in the electric storage module andtransmit the collected information to the external apparatus.

In the present embodiment, the system control unit 140 decides the orderin which the electric storage unit of each electric storage modules isto be electrically connected to the wire 106, based on the voltage ofthe electric storage unit of each electric storage module. For example,if the state of the electric storage system 100 is in the state ofcharge when the operation of the electric storage system 100 is started,the system control unit 140 electrically connects to the wire 106 theelectric storage units of the electric storage modules in the order oflowest to highest voltage of the electric storage units of the electricstorage modules. On the other hand, if the state of the electric storagesystem 100 is in the state of discharge when the operation of theelectric storage system 100 is started, the system control unit 140electrically connects to the wire 106 the electric storage units of theelectric storage modules in the order of highest to lowest voltage ofthe electric storage units of the electric storage modules. Note thatthe system control unit 140 may also decide the order in which theelectric storage unit of each electric storage module is to beelectrically connected to the wire 106, based on the terminal voltage ofeach electric storage module.

In an embodiment, the system control unit 140 may transmit to eachelectric storage module a signal for connecting the electric storageunit to the wire 106 in accordance with the decided order. In anotherembodiment, the system control unit 140 may also select the electricstorage module having the lowest voltage or the smallest SOC, or selectthe electric storage module having the highest voltage or the largestSOC, and transmit only to the selected electric storage module a signalfor connecting the electric storage unit to the wire 106.

The system control unit 140 may be realized by hardware, realized bysoftware, or realized by hardware and software. Also, the system controlunit 140 may be realized by combination of hardware and software. In anembodiment, the system control unit 140 may be realized by an analogcircuit, a digital circuit, or combination of an analog circuit and adigital circuit. In another embodiment, in a general informationprocessing device provided with a data processing device and the likehaving a CPU, a ROM, a RAM, a communication interface, and the like, thesystem control unit 140 may be realized by executing programs forcontrolling the respective units of the system control unit 140.

The programs installed in a computer to cause the computer to functionas part of the system control unit 140 according to the presentembodiment may include modules that define operations of the respectiveunits of the system control unit 140. These programs or modulescooperate with CPU and the like to cause the computer to function as therespective units of the system control unit 140.

By being read by the computer, the information processing described inthese programs functions as specific means as a result of the softwareand the above-described various types of hardware resources cooperatingwith each other. By realizing computation or processing of informationto meet the intended use of the computer in the present embodiment bythese specific means, a specific device to meet the intended use can beconstructed. The programs may be stored on a computer-readable medium ora storage device connected to a network.

Note that the reference to ‘electrically connected’ is not limited todirect connection between a particular component and another component.A third component may also be present between the particular componentand another component. Also, the reference to ‘electrically connected’is not limited to physical connection between a particular component andanother component. For example, input winding and output winding in atransformer are not physically connected but are electrically connected.Furthermore, the reference to ‘electrically connected’ means not onlythat a particular component is actually and electrically connected toanother component but also that the particular component is electricallyconnected to the other component when an electric storage cell and abalance correcting unit are electrically connected. Also, the referenceto ‘connected in series’ indicates that a particular component andanother component are electrically connected in series, and thereference to ‘connected in parallel’ indicates that a particularcomponent and another component are electrically connected in parallel.

As described above, in the present embodiment, the electric storagesystem 100 includes the two electric storage modules connected inparallel. However, the electric storage system 100 is not limited to thepresent embodiment. In another embodiment, the electric storage system100 may also have three or more electric storage modules connected inparallel.

As described above, in the present embodiment, a user performs operationfor electrically connecting the electric storage unit of the newelectric storage module 110 and the wire 106 before implementing theelectric storage module 110 in the electric storage system 100. However,the methods of implementing or replacing the electric storage module 110are not limited to the present embodiment. In another embodiment, auser, for example, operates an input unit (not shown in the drawing) ofthe electric storage system 100 and inputs an instruction to startreplacing the electric storage module 110. Examples of the input unitsinclude a keyboard, a pointing device, a touch panel, a microphone, avoice recognition system, and a gesture input system.

The system control unit 140 may perform operation for electricallydisconnecting the wire 106 and the electric storage unit of the electricstorage module (the electric storage module 120 in the presentembodiment) connected in parallel with the electric storage module 110upon accepting an instruction to start replacing the electric storagemodule 110. At this time, the system control unit 140 may also performoperation for electrically disconnecting the electric storage unit ofthe electric storage module 110 and the wire 106. For example, thesystem control unit 140 transmits to the switching element a signal forturning off a switching element arranged between a positive terminal andthe electric storage unit of each electric storage module.

The system control unit 140 acquires the voltage of the electric storageunit of each electric storage module upon detecting that the oldelectric storage module 110 has been detached and the new electricstorage module 110 has been implemented. If the electric storage unit ofthe new electric storage module 110 and the wire 106 are electricallyconnected, the system control unit 140 operates the electric storagesystem 100 by using only the electric storage module 110 until thevoltage differential between the electric storage module 110 and theelectric storage module 120 becomes an appropriate value, for example.Then, when the voltage differential between the electric storage module110 and the electric storage module 120 has become the appropriatevalue, the system control unit 140 executes operation for electricallyconnecting the electric storage module 120 and the wire 106.

On the other hand, if the electric storage unit of the new electricstorage module 110 and the wire 106 are not electrically connected, thesystem control unit 140 decides the order in which the electric storageunit of each electric storage module is to be electrically connected tothe wire 106, based on the voltage of the electric storage unit of eachelectric storage module. Subsequently, the system control unit 140electrically connects the electric storage unit of each electric storagemodule to the wire 106 in accordance with the decided order. Note that,if the electric storage unit of the new electric storage module 110 andthe wire 106 are electrically connected, the system control unit 140 mayalso first electrically disconnect the electric storage unit of the newelectric storage module 110 and the wire 106. Subsequently, the systemcontrol unit 140 may also decide the order in which the electric storageunit of each electric storage module is to be electrically connected tothe wire 106, based on the voltage of the electric storage unit of eachelectric storage module and then electrically connect the electricstorage unit of each electric storage module to the wire 106 inaccordance with the decided order.

Application Example of the Electric Storage System 100

As described above, according to the electric storage system 100 of thepresent embodiment, at least one of the electric storage module 110 andthe electric storage module 120 that are connected in parallel with theload device 12 or the charging device 14 can be implemented or replacedat an optional timing without concerns about the voltage differentialbetween the both electric storage modules. Here, the voltagedifferential between the electric storage module 110 and the electricstorage module 120 may be caused not only by the difference with respectto the state of charge or the state of discharge of the both electricstorage modules but also by the difference in the batterycharacteristics of the both electric storage modules. The batterycharacteristic of the electric storage module may be similar to thebattery characteristic of the above described electric storage unit. Thebattery characteristic of the electric storage module may be at leastone of the characteristics illustrated as the battery characteristics ofthe electric storage unit.

Because of this, according to the electric storage system 100 of thepresent embodiment, even if the battery characteristic of the electricstorage module 110 and the battery characteristic of the electricstorage module 120 are different, the electric storage module 110 andthe electric storage module 120 can be connected in parallel with theload device 12 or the charging device 14, with the electric storagemodule 110 and the electric storage module 120 prevented from beingdeteriorated or damaged. Note that in the electric storage system 100according to the present embodiment, the battery characteristic of theelectric storage module 110 and the battery characteristic of theelectric storage module 120 may be the same or different. If theelectric storage module 110 and the electric storage module 120 includesecondary batteries, the battery characteristic of the secondary batteryconstituting the electric storage unit of the electric storage module110 and the battery characteristic of the secondary battery constitutingthe electric storage unit of the electric storage module 120 may be thesame or different.

Also, a power supply system in which a plurality of power supply moduleshaving the battery characteristics different from each other can beconnected in parallel may also be constructed by a configuration similarto that of the electric storage system 100. Each power supply module canthereby be implemented or replaced at an optional timing, withdeterioration or damage of each power supply module being suppressed.Employing the configuration similar to that of the electric storagesystem 100 is particularly useful to a system in which the power supplysystem is electrically connected to an external charging device or aload device by two terminals.

The power supply module may be an example of a power supply device thatsupplies power to another apparatus. The electric storage module 110 andthe electric storage module 120 may be examples of the power supplymodules. The electric storage system 100 may be an example of the powersupply system in which a plurality of power supply devices areconfigured such that the power supply devices can be connected inparallel. The electric storage unit and the secondary battery may beexamples of power supply units that serve as power supply sources forthe power supply device.

The battery characteristic of the power supply device fluctuates due tofactors such as: (i) the deterioration state of the power supply unit;(ii) the type of the power supply unit; and (iii) the state of balancebetween the capacity and SOC. According to an embodiment, a power supplysystem is provided in which a plurality of power supply devices havingdeterioration states different from each other can be connected inparallel. Although the detail of the above described power supply systemwill be described below, according to the embodiment, the power supplysystem can be constructed, for example, by using a secondhand powersupply module (in some cases, referred to as used item, reused item, orthe like).

According to another embodiment, a power supply system is provided inwhich different types of a plurality of power supply devices can beconnected in parallel. This allows the power supply system to beconstructed superior to a power supply system constructed by combiningpower supply devices of a single type, with respect to at least one ofthe life, the reliability, the charging performance, the dischargingperformance, the energy efficiency, the temperature characteristic, andthe economy. The detail of the above described power supply system willbe described below.

As described above, in the electric storage system 100 according to thepresent embodiment, the plurality of power supply modules constitutingthe electric storage system 100 are the electric storage module 110 andthe electric storage module 120. However, the plurality of power supplymodules constituting the electric storage system 100 are not limited tothe present embodiment. In another embodiment, at least one of theplurality of power supply modules may include a primary battery or afuel battery. In another embodiment, at least one of the plurality ofpower supply modules may include a primary battery or a fuel battery,and at least one of the plurality of power supply modules may include asecondary battery. The electric storage unit, the primary battery, andthe fuel battery may be examples of the power supply units.

In these cases, by a configuration similar to that of the electricstorage module 110 and that of the electric storage module 120, thepower supply module including a primary battery or a fuel battery mayswitch the connection relationship between the primary battery or thefuel battery of the power supply module and the wire 106 based on acontrol signal from the system control unit 140 or the user operation.For example, the power supply module electrically connects the primarybattery or the fuel battery of the power supply module and the wire 106upon receiving from the system control unit 140 a signal indicatingdetection of the discharging operation. On the other hand, the powersupply module disconnects the electrical connection relationship betweenthe primary battery or the fuel battery of the power supply module andthe wire 106 upon receiving from the system control unit 140 a signalindicating detection of the charging operation. The damage ordeterioration of the primary battery or the fuel battery can thereby beprevented.

First Application Example of the Electric Storage System 100

In an embodiment, the electric storage system 100 includes a pluralityof power supply devices. The plurality of power supply devices mayinclude two power supply devices the power supply units of which havethe deterioration states different from each other. The plurality ofpower supply devices may be connected in parallel with the load device12 or the charging device 14. The electric storage system 100 may beelectrically connected to the load device 12 or the charging device 14by two terminals. At least one of the plurality of power supply devicesmay be held in the housing of the electric storage system 100 in anattachable and detachable manner. Each power supply device can therebybe individually replaced. The electric storage system 100 may include atleast one electric storage module.

Examples of the power supply devices having different deteriorationstates include power supply devices having different use histories. Forexample, the electric storage system 100 has a new power supply deviceand a secondhand power supply device. The electric storage system 100may also have a plurality of secondhand power supply devices havingdifferent use histories.

In recent years, there has been rapidly increasing demand for storagebatteries to be used in electric storage devices and the like forapplications that temporarily require a large current such as: (i) powersource of electric vehicle, PHEV (Plug-in Hybrid Electric Vehicle), andthe like; (ii) output stabilizing device for renewable energy; (iii)electric storage device for smart grid; (iv) electric storage device forstoring power during the hours when the electricity charge isinexpensive; and (v) charging station. Also, the number of storagebatteries having reached the renewal timing is increasing.

Here, the performance required for a storage battery differs dependingon the application. Because of this, even if the storage battery used ina particular application deteriorates and no longer satisfies theperformance required for the application, the storage battery can bereused by being diverted to another application in some cases. Also, asa result of the improvement in the performance of the storage battery,the life of the storage battery is longer than the life of a productincorporating the storage battery in some cases. Also in such cases, thestorage battery is preferably reused and not discarded.

If the storage battery is reused, the deterioration state of eachstorage battery differs. Because of this, the battery characteristic ofthe storage battery has been conventionally tested before the storagebattery is reused. Also, based on the test result, a power supply systemhas been constructed by combining storage batteries having the batterycharacteristics that satisfy a particular condition. However, in orderto test the battery characteristic, the storage battery needs to bedischarged after the storage battery has been full-charged, whichrequires efforts and time.

In contrast, according to the present embodiment, the electric storagesystem 100 in which a plurality of power supply devices havingdeterioration states different from each other are connected in parallelcan easily be constructed. Also, each power supply device canindividually be implemented or detached while the electric storagesystem 100 is operated. Furthermore, at least part of the test for thepower supply device can be omitted before the power supply device to bereused is incorporated in the electric storage system 100.

According to the present embodiment, each power supply device can switchthe connection relationship between its power supply unit and the wire106 based on a control signal from the system control unit 140 or theuser operation. The electric storage system 100 can thereby be safelyoperated even if the battery characteristic of the power supply deviceto be reused is not tested in advance. Also, the battery characteristicof the power supply device can be checked while the electric storagesystem 100 is operated. Then, if the battery characteristic of the powersupply device is insufficient, the power supply device can easily bereplaced.

Second Application Example of the Electric Storage System 100

In another embodiment, the electric storage system 100 includes aplurality of power supply devices. The plurality of power supply devicesmay include two power supply devices having different types of powersupply units. The plurality of power supply devices may be connected inparallel with the load device 12 or the charging device 14. The electricstorage system 100 may be electrically connected to the load device 12or the charging device 14 by two terminals. At least one of theplurality of power supply devices may be held in the housing of theelectric storage system 100 in an attachable and detachable manner. Eachpower supply device can thereby be individually replaced. The electricstorage system 100 may include at least one electric storage module.

Examples of the types of the power supply units include a primarybattery, a secondary battery, and a fuel battery. Examples of the typesof the secondary batteries include a lithium battery, a lithium-ionbattery, a lithium-sulfur battery, a sodium-sulfur battery, a lead-acidbattery, a redox flow battery, and a metal-air battery. The types of thelithium-ion batteries are not particularly limited. Examples of thetypes of the lithium-ion batteries include an iron phosphate basedbattery (sometimes referred to as LFP-based), a manganese based battery,a cobalt based battery, a nickel based battery, and a ternary basedbattery.

If the types of the power supply units included in the two power supplydevices are different from each other, the difference between the ratedvoltages of the two power supply devices exceeds a predetermined valuein some cases. Also, at least one of the difference between the chargecharacteristics and the difference between the discharge characteristicsof the two power supply devices does not satisfy the predeterminedcondition in some cases. Conventionally, the power supply system hasbeen constructed by finding power supply devices that match a particularcondition and combining them. Because of this, there has been no conceptof connecting two of such power supply devices in parallel.

In contrast, according to the present embodiment, the electric storagesystem 100 in which a plurality of power supply devices of differenttypes are connected in parallel can easily be constructed. Also, eachpower supply device can individually be implemented or detached whilethe electric storage system 100 is operated. Furthermore, at the time ofthe charging operation of the electric storage system 100, theelectrical connection relationship between the power supply unit and theload device 12 or the charging device 14 can be disconnected, dependingon the type of the power supply unit included in the power supplydevice.

According to the present embodiment, each power supply device can switchthe connection relationship between its power supply unit and the wire106 based on a control signal from the system control unit 140 or theuser operation. The electric storage system 100 can thereby be safelyoperated if the difference between the rated voltages of the two powersupply devices included in the electric storage system 100 exceeds apredetermined value or even if at least one of the difference betweenthe charge characteristics and the difference between the dischargecharacteristics of the two power supply devices does not satisfy thepredetermined condition.

Also, according to the present embodiment, the power supply system canbe constructed superior to a power supply system constructed bycombining power supply devices of a single type with respect to at leastone of the life, the reliability, the charging performance, thedischarging performance, the energy efficiency, the temperaturecharacteristic, and the economy. For example, the power supply systemthat has a high energy efficiency and also operates in a widetemperature range can be constructed by combining: (i) the power supplymodule including a lead-acid battery that operates in a relatively widetemperature range but has relatively low energy efficiency in chargingand discharging; and (ii) the power supply module including alithium-ion battery that has a high energy efficiency in charging anddischarging but has a problem in operating in low and high temperatureregions.

FIG. 2 schematically shows an example of the system configuration of theelectric storage module 110. In the present embodiment, the electricstorage module 110 includes the electric storage unit 210 that has apositive terminal 212 and a negative terminal 214, a switching unit 230,a module control unit 240, a protecting unit 250, and a balancecorrecting unit 260. Also, in the present embodiment, the electricstorage unit 210 includes an electric storage cell 222 and an electricstorage cell 224. The switching unit 230 may be an example of theswitching element. The module control unit 240 may be an example of acontrol unit. The module control unit 240 may be an example of a controldevice. The module control unit 240 may be an example of the batterycharacteristic acquiring unit. The module control unit 240 may be anexample of the output unit.

The impedance of the electric storage unit 210 may be equal to or lowerthan 1Ω or equal to or lower than 100 mΩ. The impedance of the electricstorage unit 210 may be equal to or lower than 10 mΩ, equal to or lowerthan 1 mΩ, equal to or lower than 0.8 mΩ, or equal to or lower than 0.5mΩ. The impedance of the electric storage unit 210 may be equal to orhigher than 0.1 mΩ. The impedance of the electric storage unit 210 maybe equal to or higher than 0.1 mΩ and equal to or lower than 1Ω, may beequal to or higher than 0.1 mΩ and equal to or lower than 100 mu, may beequal to or higher than 0.1 mΩ and equal to or lower than 10 mΩ, or maybe equal to or higher than 0.1 mΩ and equal to or lower than 1 mΩ.

According to the electric storage system 100 of the present embodiment,for example, if one of the plurality of electric storage modulesconnected in parallel is replaced, the voltage of the electric storagemodule to be newly added to the electric storage system and the voltageof the remaining electric storage module may not match each other withhigh precision. Because of this, the electric storage module 110 can beeasily and quickly replaced even if the impedance of the electricstorage unit 210 is small.

In the present embodiment, the electric storage cell 222 and theelectric storage cell 224 are connected in series. The electric storagecell 222 and the electric storage cell 224 may be secondary batteries orcapacitors. At least one of the electric storage cell 222 and theelectric storage cell 224 may be a lithium-ion battery. At least one ofthe electric storage cell 222 and the electric storage cell 224 mayfurther include a plurality of electric storage cells connected inseries, in parallel, or in a matrix inside the electric storage cell.

In the present embodiment, the positive terminal 212 of the electricstorage unit 210 is electrically connected to the wire 106 via thepositive terminal 112 and the switching unit 230 of the electric storagemodule 110. On the other hand, the negative terminal 214 of the electricstorage unit 210 is electrically connected to the wire 106 via thenegative terminal 114 of the electric storage module 110. However, theelectric storage module 110 is not limited to the present embodiment. Inanother embodiment, the negative terminal 214 of the electric storageunit 210 is electrically connected to the wire 106 via the negativeterminal 114 and the switching unit 230 of the electric storage module110. On the other hand, the positive terminal 212 of the electricstorage unit 210 is electrically connected to the wire 106 via thepositive terminal 112 of the electric storage module 110.

The switching unit 230 is arranged between the wire 106 and the electricstorage unit 210. In the present embodiment, the switching unit 230switches the connection state of the wire 106 and the electric storageunit 210 based on a signal generated by the module control unit 240. Theelectric storage unit 210 can thereby be electrically connected to thewire 106 or electrically disconnected from the wire 106. If the electricstorage module 110 is implemented in the electric storage system 100,the electric storage module 110 may be loaded into the electric storagesystem 100, with the electric storage unit 210 and the wire 106electrically disconnected by the switching unit 230. The damage ordeterioration of the electric storage module 110 can thereby beprevented.

The switching unit 230 may be realized by hardware, realized bysoftware, or realized by combination of hardware and software. Theswitching unit 230 may be realized by an analog circuit, a digitalcircuit, or combination of an analog circuit and a digital circuit. Theswitching unit 230 may have one or more elements. The switching unit 230may also have one or more switching elements. Each of the one or moreswitching elements may be arranged between the positive terminal 112 andthe positive terminal 212 or between the negative terminal 114 and thenegative terminal 214. Examples of the switching elements include arelay, a thyristor, and a transistor. The thyristor may be abi-directional thyristor (in some cases, referred to as triac). Thetransistor may be a semiconductor transistor. The semiconductortransistor may be a bipolar transistor or a field effect transistor. Thefield effect transistor may be a MOSFET.

The module control unit 240 controls the current flowing between theelectric storage unit 210 of the electric storage module 110 and thewire 106. In the present embodiment, if the terminal voltage of theswitching unit 230 (the voltage between the positive terminal 112 andthe positive terminal 212 in the present embodiment) satisfies apredetermined condition, the module control unit 240 controls theswitching unit 230 such that the switching unit 230 electricallyconnects the electric storage unit 210 and the wire 106. The switchingunit 230 may electrically connect the electric storage unit 210 and thewire 106 by electrically connecting the electric storage unit 210 andthe positive terminal 112.

On the other hand, if the terminal voltage of the switching unit 230does not satisfy the predetermined condition, the module control unit240 controls the switching unit 230 such that the switching unit 230electrically disconnects the electric storage unit 210 and the wire 106or disconnects the electric storage unit 210 and the positive terminal112. The switching unit 230 may electrically disconnect the electricstorage unit 210 and the wire 106 by electrically disconnecting theelectric storage unit 210 and the positive terminal 112.

The predetermined condition may be a condition that the absolute valueof the terminal voltage of the switching unit 230 is within apredetermined range. The predetermined range may be equal to or lowerthan 3 V, equal to or lower than 1 V, equal to or lower than 0.1 V,equal to or lower than 10 mV, or equal to or lower than 1 mV. Also, thepredetermined range may be equal to or higher than 0.5 mV or equal to orhigher than 1 mV. The predetermined range may be equal to or higher than0.5 mV or equal to or lower than 3 V. Also, the predetermined range maybe equal to or higher than 1 mV and equal to or lower than 3 V, may beequal to or higher than 1 mV and equal to or lower than 1 V, may beequal to or higher than 1 mV and equal to or lower than 0.1 V, may beequal to or higher than 1 mV and equal to or lower than 10 mV, may beequal to or higher than 10 mV and equal to or lower than 1 V, may beequal to or higher than 10 mV and equal to or lower than 0.1 V, or maybe equal to or higher than 0.1 V and equal to or lower than 1 V. Notethat the terminal voltage of the switching unit 230 may be the voltagebetween the positive terminal 112 and the positive terminal 212 or thevoltage between the wire 106 and the electric storage unit 210.

The predetermined range may be set based on the impedance of theelectric storage unit 210. The predetermined range may be set based onthe rated current or allowable current of the electric storage unit 210.The predetermined range may be set based on the impedance of theelectric storage unit 210 and on the rated current or allowable currentof the electric storage unit 210. The predetermined range may be setbased on the rated current or allowable current of an element that isincluded in elements constituting the electric storage module 110 andhas the lowest rated current or allowable current. The predeterminedrange may be set based on the impedance of the electric storage module110 and on the rated current or allowable current of the element that isincluded in the elements constituting the electric storage module 110and has the lowest rated current or allowable current.

If the electric storage module is replaced, the wire 106 and theelectric storage unit 210 of the newly implemented electric storagemodule can thereby be maintained electrically disconnected until thevoltage differential between the newly implemented electric storagemodule and the already implemented electric storage module falls withinthe predetermined range. Then, when the voltage differential between thenewly implemented electric storage module and the already implementedelectric storage module have fallen within the predetermined range bycharging or discharging the already implemented electric storage module,the electric storage unit of the newly implemented electric storagemodule is electrically connected to the wire 106. In this way, accordingto the present embodiment, the newly implemented electric storage moduleand the other electric storage module can be automatically connected.

In the present embodiment, the module control unit 240 receives from thesystem control unit 140 a signal indicating that the terminal voltage ofthe electric storage module 110 is lower than the terminal voltage ofthe other electric storage module. If the module control unit 240receives the above described signal when the electric storage system 100shifts to the state of charge, the module control unit 240 controls theswitching unit 230 such that the switching unit 230 electricallyconnects the electric storage unit 210 and the wire 106. The pluralityof electric storage modules 110 connected in parallel can thereby beefficiently charged.

In the present embodiment, the module control unit 240 receives from thesystem control unit 140 a signal indicating that the terminal voltage ofthe electric storage module 110 is higher than the terminal voltage ofthe other electric storage module. If the module control unit 240receives the above described signal when the electric storage system 100shifts to the state of discharge, the module control unit 240 controlsthe switching unit 230 such that the switching unit 230 electricallyconnects the electric storage unit 210 and the wire 106. The pluralityof electric storage modules 110 connected in parallel can thereby beefficiently discharged.

In the present embodiment, the module control unit 240 receives from theprotecting unit 250 a signal indicating that the terminal voltage of theelectric storage cell 222 or the terminal voltage of the electricstorage cell 224 is not in the predetermined range. When the modulecontrol unit 240 has received the signal, the module control unit 240controls the switching unit 230 such that the switching unit 230electrically disconnects the electric storage unit 210 and the wire 106.The deterioration or damage of the electric storage unit 210 due toovercharge or over discharge can thereby be suppressed.

In the present embodiment, the module control unit 240 accepts useroperation and receives an instruction for turning on or turning off theswitching unit 230 from the user. When the module control unit 240 hasreceived the instruction from the user, the module control unit 240controls the switching unit 230 in accordance with the instruction.

In the present embodiment, the module control unit 240 may acquireinformation related to the battery characteristic of the electricstorage unit 210. The module control unit 240 may output to an externalapparatus the information related to the battery characteristic of theelectric storage unit 210. The external apparatus can thereby use theinformation related to the battery characteristic of the electricstorage unit 210. Examples of the external apparatuses include the loaddevice 12 and the charging device 14. The external apparatus may be anoutput device that outputs information to a user.

The module control unit 240 may be realized by hardware or realized bysoftware. Also, the module control unit 240 may be realized bycombination of hardware and software. In an embodiment, the modulecontrol unit 240 may be realized by an analog circuit, a digitalcircuit, or combination of an analog circuit and a digital circuit. Inanother embodiment, in a general information processing device providedwith a data processing device and the like having a CPU, a ROM, a RAM,an communication interface, and the like, the module control unit 240may be realized by executing a program for controlling the modulecontrol unit 240.

The programs installed into a computer to cause the computer to functionas part of the module control unit 240 according to the presentembodiment may include modules that define operations of the respectiveunits of the module control unit 240. These programs or modulescooperate with CPU or the like to cause the computer to function as therespective units of the module control unit 240.

By being read by the computer, the information processing described inthese programs functions as specific means as a result of the softwareand the above described various types of hardware resources cooperatingwith each other. By realizing computation or processing of informationto meet the intended use of the computer in the present embodiment bythese specific means, a specific device to meet the intended use can beconstructed. The programs may be stored on a computer-readable medium ora storage device connected to a network. The computer-readable mediummay be a non-transitory computer-readable medium.

The protecting unit 250 protects the electric storage unit 210. In thepresent embodiment, the protecting unit 250 protects the electricstorage unit 210 from overcharge and over discharge. When the protectingunit 250 has detected that the terminal voltage of the electric storagecell 222 or the terminal voltage of the electric storage cell 224 is notin the predetermined range, the protecting unit 250 transmits to themodule control unit 240 a signal indicating the content of thedetection. The protecting unit 250 may transmit to the system controlunit 140 the information related to the terminal voltage of the electricstorage unit 210. The protecting unit 250 may be realized by hardware,realized by software, or realized by combination of hardware andsoftware. The protecting unit 250 may be realized by an analog circuit,a digital circuit, or combination of an analog circuit and a digitalcircuit.

The balance correcting unit 260 equalizes the voltage of the pluralityof electric storage cells. The operating principle of the balancecorrecting unit 260 is not particularly limited, and an optional balancecorrecting device can be used. If the electric storage unit 210 hasthree or more electric storage cells, the electric storage module 110may have a plurality of balance correcting units 260. For example, ifthe electric storage unit 210 has n (n is an integer equal to or largerthan 2) electric storage cells, the electric storage module 110 has n−1balance correcting unit(s) 260.

The balance correcting unit 260 may be realized by hardware, realized bysoftware, or realized by combination of hardware and software. Thebalance correcting unit 260 may be realized by an analog circuit, adigital circuit, or combination of an analog circuit and a digitalcircuit. In an embodiment, the balance correcting unit 260 is anactive-type balance correcting device. The active-type balancecorrecting unit may be a balance correcting unit that transfers electriccharges between two electric storage cells via an inductor as describedin Japanese Patent Application Publication No. 2006-067742. Also, theactive-type balance correcting unit may be a balance correcting unitthat transfers electric charges via a capacitor as described in JapanesePatent Application Publication No. 2012-210109. In another embodiment,the balance correcting unit 260 may be a passive-type balance correctingdevice. The passive-type balance correcting device releases extraelectric charges by using an external resistor, for example.

As described above, in the present embodiment, the electric storage unit210 has the two electric storage cells connected in series. However, theelectric storage unit 210 is not limited to the present embodiment. Inanother embodiment, the electric storage unit 210 may also have three ormore electric storage cells connected in series. Also, the electricstorage unit 210 may have a plurality of electric storage cellsconnected in parallel or a plurality of electric storage cells connectedin a matrix.

FIG. 3 schematically shows an example of the system configuration of themodule control unit 240. In the present embodiment, the module controlunit 240 includes a determining unit 310, a receiving unit 320, and asignal generating unit 330. The module control unit 240 may also includea module information acquiring unit 340, a module information storingunit 350, and a module information transmitting unit 360. The receivingunit 320 may be an example of the first signal receiving unit, secondsignal receiving unit, and third signal receiving unit. The moduleinformation acquiring unit 340 may be an example of the batterycharacteristic acquiring unit. The module information transmitting unit360 may be an example of the output unit.

As described in the present embodiment, the module control unit 240includes the module information acquiring unit 340, the moduleinformation storing unit 350, and the module information transmittingunit 360. However, the electric storage system 100 is not limited to thepresent embodiment. In another embodiment, the system control unit 140may also include at least one of the module information acquiring unit340, the module information storing unit 350, and the module informationtransmitting unit 360.

The determining unit 310 determines whether or not the terminal voltageof the switching unit 230 is within a predetermined range. Thedetermining unit 310 transmits to the signal generating unit 330 asignal indicating the determination result. The determining unit 310 maybe an optional comparator or a comparator circuit. The determining unit310 may be a window comparator.

The receiving unit 320 receives at least one of a signal from the systemcontrol unit 140, a signal from the protecting unit 250, and aninstruction from a user. The receiving unit 320 transmits to the signalgenerating unit 330 a signal corresponding to the receive information.

The signal generating unit 330 receives the signal from at least one ofthe determining unit 310 and the receiving unit 320. The signalgenerating unit 330 generates a signal for controlling the switchingunit 230 based on the received information. The signal generating unit330 transmits the generated signal to the switching unit 230.

In an embodiment, if the determining unit 310 has determined that theterminal voltage of the switching unit 230 is within a predeterminedrange, the signal generating unit 330 generates a signal for turning onthe switching element of the switching unit 230. In another embodiment,if the determining unit 310 has determined that the terminal voltage ofthe switching unit 230 is not in the predetermined range, the signalgenerating unit 330 generates a signal for turning off the switchingelement of the switching unit 230.

The signal generating unit 330 may generate or transmit a signalsubsequent to the passage of a predetermined amount of time after thedetermining unit 310 determines whether or not the terminal voltage ofthe switching unit 230 is within the predetermined range. Themalfunction due to noise or the like can thereby be prevented. Also, theelectric storage unit 210 and the wire 106 can be prevented from beingelectrically connected immediately after the electric storage module 110is loaded into the electric storage system 100.

In the present embodiment, the signal generating unit 330 generates asignal for controlling the switching element of the switching unit 230based on a signal received by the receiving unit 320. In an embodiment,if the receiving unit 320 has received from the system control unit 140a signal for turning on the switching element of the switching unit 230,the signal generating unit 330 generates a signal for turning on theswitching element of the switching unit 230.

In another embodiment, if the receiving unit 320 has received from theprotecting unit 250 a signal for turning off the switching element ofthe switching unit 230, the signal generating unit 330 generates asignal for turning off the switching element of the switching unit 230.Furthermore, in another embodiment, if the receiving unit 320 hasaccepted an instruction from a user, the signal generating unit 330generates a signal for causing the switching element of the switchingunit 230 to operate as instructed by the user.

In the present embodiment, the module information acquiring unit 340acquires the information related to the battery characteristic of theelectric storage unit 210. The module information acquiring unit 340 mayalso acquire the information related to the battery characteristic ofthe electric storage unit 210 by measuring the battery characteristic ofthe electric storage unit 210. The module information acquiring unit 340may also acquire information that is input by a manufacturer, a seller,or the like at the time of shipping, testing, or selling and is relatedto the battery characteristic of the electric storage unit 210.

The module information acquiring unit 340 may store the informationrelated to the battery characteristic of the electric storage unit 210in the module information storing unit 350. Although the specificconfiguration of the module information acquiring unit 340 is notparticularly limited, the module information acquiring unit 340 may be acontroller that controls reading data from and writing data into themodule information storing unit 350. In the present embodiment, themodule information storing unit 350 stores the information that has beenacquired by the module information acquiring unit 340 and is related tothe battery characteristic of the electric storage unit 210.

In the present embodiment, the module information transmitting unit 360transmits to the system control unit 140 the information that has beenacquired by the module information acquiring unit 340 and is related tothe battery characteristic of the electric storage unit 210. The moduleinformation transmitting unit 360 may also transmit to an externalapparatus the information that has been acquired by the moduleinformation acquiring unit 340 and is related to the batterycharacteristic of the electric storage unit 210. The module informationtransmitting unit 360 may transmit the information related to thebattery characteristic of the electric storage unit 210 in response to arequest by the external apparatus or transmit the information related tothe battery characteristic of the electric storage unit 210 at apredetermined timing. The module information transmitting unit 360 mayalso refer to the module information storing unit 350 and transmit tothe system control unit 140 or the external apparatus the informationrelated to the battery characteristic of the electric storage unit 210.

FIG. 4 schematically shows an example of the system configuration of thesystem control unit 140. In the present embodiment, the system controlunit 140 includes a state managing unit 410, a module selecting unit420, and a signal generating unit 430. The state managing unit 410 maybe an example of the battery characteristic acquiring unit. The statemanaging unit 410 may be an example of the output unit.

In the present embodiment, the state managing unit 410 manages the stateof the electric storage system 100. The state managing unit 410 maymanage the state of the electric storage module 110 and the state of theelectric storage module 120. The state managing unit 410 may monitor thestate of each of the electric storage module 110 and the electricstorage module 120. The state managing unit 410 may monitor the electricstorage module 110 and the electric storage module 120 and also acquireinformation related to the battery characteristic of each of theelectric storage module 110 and the electric storage module 120. Thestate managing unit 410 may also transmit to an external apparatus theinformation acquired by monitoring the electric storage module 110 andthe electric storage module 120.

The state managing unit 410 may measure the battery characteristic ofeach electric storage module while the electric storage system 100 isoperated. If the battery characteristic of the electric storage moduledoes not satisfy a predetermined condition, the state managing unit 410may output information indicating that the performance of the electricstorage module is insufficient, to an output device that outputsinformation to a user. The state managing unit 410 may also outputidentification information of the electric storage module and theinformation indicating that the performance of the electric storagemodule is insufficient.

The user can thereby easily distinguish the electric storage modulehaving the insufficient performance and can replace the electric storagemodule. According to the present embodiment, for example, if theelectric storage system 100 is constructed using a reused electricstorage module(s), at least part of the test for the electric storagemodule to be reused can be omitted.

In an embodiment, when the electric storage system 100 shifts to thestate of charge, the module selecting unit 420 selects an electricstorage module that is included in the plurality of electric storagemodules in the electric storage system 100 and has the lowest terminalvoltage. For example, the module selecting unit 420 compares theterminal voltage of the electric storage module 110 and the terminalvoltage of the electric storage module 120 and then selects the electricstorage module having the lower terminal voltage. The module selectingunit 420 transmits to the signal generating unit 430 a signal indicatingthe selected electric storage module.

In another embodiment, when the electric storage system 100 shifts tothe state of discharge, the module selecting unit 420 selects theelectric storage module that is included in the plurality of electricstorage modules in the electric storage system 100 and has the highestterminal voltage. For example, the module selecting unit 420 comparesthe terminal voltage of the electric storage module 110 and the terminalvoltage of the electric storage module 120 and then selects the electricstorage module having the higher terminal voltage. The module selectingunit 420 transmits to the signal generating unit 430 a signal indicatingthe selected electric storage module.

In the present embodiment, the signal generating unit 430 generates asignal for turning on the switching element of the switching unit 230 inthe electric storage module selected by the module selecting unit 420.The signal generating unit 430 transmits the generated signal to themodule control unit 240. In another embodiment, the signal generatingunit 430 may also generate a signal for turning off the switchingelement of the switching unit 230 in the electric storage moduleselected by the module selecting unit 420.

FIG. 5 schematically shows an example of the circuit configuration ofthe electric storage module 110. Note that FIG. 5 does not show theprotecting unit 250 and wires associated to the protecting unit 250 inorder to simplify explanation.

In the present embodiment, the switching unit 230 includes a transistor510, a resistor 512, a resistor 514, a diode 516, a transistor 520, aresistor 522, a resistor 524, and a diode 526. The transistor 510 andthe transistor 520 may be examples of the switching element. Asdescribed in the present embodiment, the transistor 510 and thetransistor 520 are used as the switching elements of the switching unit230. However, the switching element of the switching unit 230 is notlimited to the present embodiment. In another embodiment, a singleswitching element may be used as the switching element of the switchingunit 230.

In the present embodiment, the module control unit 240 includes thedetermining unit 310, the signal generating unit 330, a switch 592, anda switch 594. In the present embodiment, the determining unit 310includes a transistor 530, a resistor 532, a transistor 540, a resistor542, a resistor 552, and a resistor 554. The signal generating unit 330includes a transistor 560, a capacitor 570, a resistor 572, and atransistor 580. The switch 592 and the switch 594 may be examples of thereceiving unit 320.

Then, the detail of each unit of the switching unit 230 and the modulecontrol unit 240 will be described. In the switching unit 230 of thepresent embodiment, the transistor 510 is a MOSFET, and even if thetransistor 510 is in the OFF state, the current may flow from thepositive terminal 212 to the positive terminal 112 due to a parasiticdiode (not shown in the drawing) equivalently formed between the sourceand drain of the transistor 510. Similarly, the transistor 520 is aMOSFET, and even if the transistor 520 is in the OFF state, the currentmay flow from the positive terminal 112 to the positive terminal 212 dueto a parasitic diode (not shown in the drawing) equivalently formedbetween the source and drain of the transistor 520.

In the present embodiment, the transistor 510 and the transistor 520 areset to the OFF state at the initial setting. If the transistor 580 isturned on when the electric storage system 100 is charged, the currentflows from the positive terminal 112 to the negative terminal 114 viathe resistor 512, the resistor 514, and the transistor 580. As a result,the voltage is applied to the gate of the transistor 510, and thetransistor 510 is turned on. The current is thereby allowed to flow fromthe positive terminal 112 to the positive terminal 212 via the parasiticdiode equivalently formed between the source and drain of the transistor520.

On the other hand, if the transistor 580 is turned on when the electricstorage system 100 is discharged, the current flows from the positiveterminal 212 to the negative terminal 214 via the resistor 522, theresistor 524, and the transistor 580. As a result, the voltage isapplied to the gate of the transistor 520, and the transistor 520 isturned on. The current is thereby allowed to flow from the positiveterminal 212 to the positive terminal 112 via the parasitic diodeequivalently formed between the source and drain of the transistor 510.

The voltage that is applied to the gate of the transistor 510 or thegate of the transistor 520, with the transistor 580 turned on, may be anexample of a signal for turning on the switching element of theswitching unit 230. Similarly, the voltage that is applied to the gateof the transistor 510 or the gate of the transistor 520, with thetransistor 580 turned off, may be an example of a signal for turning offthe switching element of the switching unit 230.

In the present embodiment, the values of the resistor 512 and theresistor 514 are set such that the transistor 510 can certainly beturned on and off in a power saving manner. Also, the values of theresistor 522 and the resistor 524 are set such that the transistor 520can certainly be turned on and off in a power saving manner.

In the present embodiment, the diode 516 is arranged between theresistor 514 and the resistor 524. The diode 516 allows the current toflow in a direction from the resistor 514 toward the resistor 524 butdoes not allow the current to flow in a direction from the resistor 524toward the resistor 514. By providing the diode 516, the current can beprevented from leaking from the positive terminal 212 to the positiveterminal 112 through the route of the resistor 522, the resistor 524,the resistor 514, and the resistor 512 when the switching unit 230electrically disconnects the positive terminal 112 and the positiveterminal 212.

In the present embodiment, the diode 526 is arranged between theresistor 514 and the resistor 524. The diode 526 allows the current toflow in the direction from the resistor 524 toward the resistor 514 butdoes not allow the current to flow in the direction from the resistor514 toward the resistor 524. By providing the diode 526, the current canbe prevented from leaking from the positive terminal 112 to the positiveterminal 212 through the route of the resistor 512, the resistor 514,the resistor 524, and the resistor 522 when the switching unit 230electrically disconnects the positive terminal 112 and the positiveterminal 212.

In the module control unit 240 of the present embodiment, the transistor530 and the transistor 540 of the determining unit 310 are set to theOFF state at the initial setting. Also, the transistor 560 and thetransistor 580 of the signal generating unit 330 are set to the OFFstate at the initial setting.

According to the present embodiment, if the terminal voltage of theswitching unit 230 is lower than a first value, which is predeterminedsuch that the positive terminal 112 side is set positive, the value ofthe resistor 532 is set such that the transistor 530 is turned on. Thevalue of the resistor 532 is preferably set such that the current thatleaks when the switching unit 230 is in the OFF state becomes verysmall. Also, the value of the resistor 542 is set such that thetransistor 540 is turned on if the terminal voltage of the switchingunit 230 is higher than a predetermined second value. The value of theresistor 542 is preferably set such that the current that leaks when theswitching unit 230 is in the OFF state becomes very small. Note that,according to the present embodiment, the terminal voltage of theswitching unit 230 is equal to the voltage differential between thepositive terminal 112 and the positive terminal 212.

If the terminal voltage of the switching unit 230 is lower than thepredetermined first value, the transistor 530 is turned on, and thevoltage is applied from the electric storage unit 210 to the base of thetransistor 560 via the positive terminal 212, transistor 530, and theresistor 552. Accordingly, the transistor 560 is turned on. Although thevoltage from the positive terminal 112 is applied to the base of thetransistor 580, the transistor 580 is prevented from being turned onwhile the transistor 560 is turned on. As a result, the transistor 580is turned off.

On the other hand, if the terminal voltage of the switching unit 230 ishigher than the predetermined the second value, the transistor 540 isturned on, and the voltage is applied from the positive terminal 112 tothe base of the transistor 560 via the transistor 540 and the resistor554. Accordingly, the transistor 560 is turned on. As a result, thetransistor 580 is turned off.

In the present embodiment, the value of the resistor 552 is set suchthat the power consumption can be reduced to the extent that thetransistor 560 can be turned on when the transistor 530 is in the ONstate. The value of the resistor 554 is set such that the powerconsumption can be reduced to the extent that the transistor 560 can beturned on when the transistor 540 is in the ON state.

The capacity of the capacitor 570 is set such that the transistor 560 isturned on before the voltage from the positive terminal 112 is appliedto the base of the transistor 580 and the transistor 580 is turned on.The signal generating unit 330 can thereby generate a signal subsequentto the passage of a predetermined amount of time after the determiningunit 310 determines whether or not the terminal voltage of the switchingelement is within the predetermined range.

In contrast, if the terminal voltage of the switching unit 230 is in therange defined by the first value and the second value, the transistor530 and the transistor 540 remain the OFF state, and the transistor 560also remains the OFF state. Because of this, the voltage is applied fromthe positive terminal 112 to the base of the transistor 580 via theresistor 572, so that the transistor 580 is turned on.

The switch 592 and the switch 594 may be manual switches or switchingelements such as relays, thyristors, and transistors. A signal 52indicating that the switching unit 230 will be turned on may be input tothe switch 592. A signal 54 indicating that the switching unit 230 willbe turned off may be input to the switch 594.

If the switch 592 is turned on, the switching unit 230 can be turned onregardless of whether the transistor 580 is turned on or turned off. Ifthe switch 594 is turned on, the transistor 580 can be turned offregardless of whether the transistor 560 is turned on or turned off. Asa result, the switching unit 230 can be turned off.

FIG. 6 schematically shows an example of a system configuration of aswitching unit 630. The switching unit 630 differs from the switchingunit 230 described in association with FIG. 5 in that the switching unit630 has a relay 632 connected in parallel with the transistor 510 andthe transistor 520. The switching unit 630 may have the configurationsimilar to that of the switching unit 230 in the other respects. In thepresent embodiment, the transistor 510 and the transistor 520 may besemiconductor transistors. The transistor 510 and the transistor 520 maybe field effect transistors (FET).

Although the relay circuit has a superior characteristic that theresistance is small when the circuit is turned on, the relay circuitresponds relatively slowly. Because of this, for example, if the loaddevice is a device having pulse current pattern such as a motor, and ifthe voltage greatly fluctuates in a short period of time, it isdifficult for the relay circuit to be turned on upon receiving a signalfrom the signal generating unit 330. On the other hand, although thesemiconductor transistor consumes power more than the relay circuit, thesemiconductor transistor is superior in the responsiveness. According tothe switching unit 630 of the present embodiment, the transistor 510 orthe transistor 520 using the semiconductor transistor, and the relay 632using the relay circuit are connected in parallel.

Because of this, if the switching unit 230 has received from the signalgenerating unit 330 a signal for turning on the switching unit 230,first, the transistor 510 or the transistor 520 quickly responds andturns on the switching unit 230. Subsequently, with some delay, therelay 632 is turned on. Then, when the relay 632 is turned on, the relay632 having a small resistance is connected in parallel with thetransistor 510 and the transistor 520. Consequently, the combinedresistance becomes small, and then the power loss can be reduced.

An electric storage module 710 is now explained with reference to FIG. 7and FIG. 8. FIG. 7 schematically shows an example of a systemconfiguration of the electric storage module 710. FIG. 8 schematicallyshows an example of a system configuration of a switching unit 730. FIG.8 shows a parasitic diode 842 of the transistor 510 and a parasiticdiode 844 of the transistor 520 in order to facilitate understanding onthe operation of the transistor 510 and the transistor 520.

The electric storage module 710 differs from the electric storage module110 described in association with FIG. 2 in that the electric storagemodule 710 has the switching unit 730 instead of the switching unit 230and that a signal from the protecting unit 250 is transmitted to theswitching unit 730, not to the module control unit 240. The electricstorage module 710 may have the configuration similar to that of theelectric storage module 110 in the other respects.

In the present embodiment, the switching unit 730 receives from themodule control unit 240 a signal for turning on or turning off theswitching unit 730. Also, the switching unit 730 receives from theprotecting unit 250 a signal for turning off the switching unit 730.

According to the present embodiment, the transistor 510 is turned on ifa signal 82 for turning on the switching element of the switching unit730 is input to a logic circuit 852 and a signal 88 indicating that theelectric storage unit 210 is in the state of overcharge is not input tothe logic circuit 852. Also, the transistor 520 is turned on if thesignal 82 for turning on the switching element of the switching unit 730is input to a logic circuit 854 and the signal 86 indicating that theelectric storage unit 210 is in the state of over discharge is not inputto the logic circuit 854.

FIG. 9 schematically shows an example of a system configuration of anelectric storage system 900. The electric storage system 900 differsfrom the electric storage system 100 in that the electric storage system900 includes a plurality of electric storage modules 110 connected in amatrix. The electric storage system 900 may have the configurationsimilar to that of the electric storage system 100 in the otherrespects. In the present embodiment, a first block including threeelectric storage modules 110 and a diode 902 connected in parallel and asecond block including three electric storage modules 110 and a diode904 connected in parallel are connected in series.

According to the present embodiment, when the electric storage system900 is discharged, all of the plurality of electric storage modules 110included in a particular block continue being discharged until theyarrive at completely discharged state, and then the discharge from theblock stops. According to the present embodiment, even if the dischargefrom the above described block stops, the diode 902 allows the currentto flow. The power supply by the electric storage system 900 can therebybe continued. Because of this, the output voltage decreases stepwisewhile the electric storage system 900 discharges power.

Similarly, when the electric storage system 900 is charged, theplurality of electric storage modules 110 included in a particular blockare sequentially disconnected from the electric storage system 900 uponcompletion of charging on the first-completed, first-disconnected basis.Then, eventually charging all of the electric storage modules 110 iscompleted.

According to the present embodiment, the diode 902 and the diode 904 areplaced so as to allow the current to flow in a direction (in some cases,referred to as discharge direction) from the connection terminal 104 tothe connection terminal 102. Because of this, even if the switchingunits 230 of all the electric storage modules 110 included in aparticular block are turned off, the current can be maintained. On theother hand, once the switching units 230 of all the electric storagemodules 110 included in the particular block are turned off, subsequentcharging becomes difficult.

According to the present embodiment, if the electric storage system 900is charged, the system control unit 140 first detects the terminalvoltage in each block and checks whether there is a block in which theterminal voltage is 0. Upon finding the block in which the terminalvoltage is 0, the system control unit 140 transmits to one of theplurality of electric storage modules 110 included in the block a signalfor turning on the switching element of the switching unit 230. Thesystem control unit 140 may transmit a signal for turning on theswitching element of the switching unit 230 to the electric storagemodule 110 that is included in the plurality of electric storage modules110 in the above described block and has the lowest terminal voltage.Subsequently, the system control unit 140 starts charging the electricstorage system 900.

As described above, in the present embodiment, the diode 902 and thediode 904 are placed so as to allow the current to flow in the dischargedirection. However, the electric storage system 900 is not limited tothe present embodiment. In another embodiment, the diode 902 and thediode 904 may be Zener diodes. Even if charging all of the electricstorage modules 110 included in a particular block is completed, and allthe electric storage modules 110 included in the block are disconnectedfrom the electric storage system 900, charging another block connectedin series with the above described particular block can thereby becontinued in the electric storage system 900.

If the electric storage system 900 is discharged in this case, thesystem control unit 140 may, prior to the start of the discharge, detectthe terminal voltage in each group and check whether there is a group inwhich the terminal voltage is 0. Subsequently, the system control unit140 may transmit a signal for turning on the switching element of theswitching unit 230 to one of the plurality of electric storage modules110 included in the block in which the terminal voltage is 0.

Other examples of the electric storage module 110 are described withreference to FIG. 10 to FIG. 17. The matters described with respect tothe electric storage module 110 and its each unit may be applied toanother example of the electric storage module 110 and its each unit, inthe range that technical contradiction does not occur. Also, the mattersdescribed with respect to another example of the electric storage module110 and its each unit may be applied to the electric storage module 110and its each unit. As to the matters described with respect to each unitof the electric storage module 110 with reference to FIG. 10 to FIG. 17,the description may be omitted in some cases.

FIG. 10 schematically shows an example of the system configuration of anelectric storage module 1010. In the present embodiment, the electricstorage module 1010 includes the positive terminal 112, the negativeterminal 114, and the electric storage unit 210. The electric storagemodule 1010 may include the switching unit 230. The electric storagemodule 1010 may include the protecting unit 250. The electric storagemodule 1010 may include the balance correcting unit 260. In the presentembodiment, the electric storage module 1010 includes a currentdetecting element 1020 and a module control unit 1040.

The electric storage module 1010 may be an example of a control deviceand a control system. The module control unit 1040 may be an example ofa control device. The switching unit 230 may be an example of anadjusting unit, a first current adjusting unit, and a second currentadjusting unit.

In the present embodiment, the switching unit 230 adjusts the currentflowing between the wire 106 and the electric storage unit 210. In anembodiment, the switching unit 230 electrically connects the wire 106and the electric storage unit 210 or electrically disconnects the wire106 and the electric storage unit 210. In another embodiment, theswitching unit 230 increases or decreases the above described current byvarying the resistance value of the path between the wire 106 and theelectric storage unit 210, for example.

In the present embodiment, one end of the switching unit 230 iselectrically connected to the wire 106 via the positive terminal 112 andthe current detecting element 1020. The other end of the switching unit230 is electrically connected to the positive terminal 212 of theelectric storage unit 210. The information indicating the terminalvoltage of the switching unit 230 may be used as the informationindicating the difference between the potential of the wire 106 or thevoltage applied to the wire 106 (in some cases, simply referred to asvoltage of the wire 106) and potential of a terminal of the electricstorage unit 210 (for example, the positive terminal 212) or voltageapplied to the terminal (in some cases, simply referred to as voltage ofthe electric storage unit 210, voltage of the terminal, or the like).

In an embodiment, the switching unit 230 adjusts at least the magnitudeof the current flowing between the wire 106 and the electric storageunit 210 in a direction from the positive terminal 212 of the electricstorage unit 210 toward the positive terminal 112 (in some cases,referred to as discharge direction). In another embodiment, theswitching unit 230 adjusts at least the magnitude of the current flowingbetween the wire 106 and the electric storage unit 210 in a directionfrom the positive terminal 112 toward the positive terminal 212 of theelectric storage unit 210 (in some cases, referred to as chargedirection). In still another embodiment, the switching unit 230 adjuststhe magnitude of the current flowing between the wire 106 and theelectric storage unit 210 in the discharge direction and the magnitudeof the current flowing between the wire 106 and the electric storageunit 210 in the charge direction.

In the present embodiment, the electric storage module 1010 differs fromthe electric storage module 110 in that the electric storage module 1010includes the current detecting element 1020. The electric storage module1010 differs from the electric storage module 110 in that the electricstorage module 1010 includes the module control unit 1040 instead of themodule control unit 240. With respect to the configuration other thanthe above described differences, the electric storage module 1010 mayhave the features similar to those of the corresponding configuration ofthe electric storage module 110.

In the present embodiment, the current detecting element 1020 is usedfor acquiring information indicating the current flowing between thewire 106 and the electric storage unit 210. Examples of the informationindicating the current include the presence or absence of the current,the magnitude of the current, and the direction of the current. In thepresent embodiment, the electric storage module 1010 acquires theinformation related to the current flowing between the wire 106 and theelectric storage unit 210 by measuring the terminal voltage of thecurrent detecting element 1020.

In the present embodiment, the current detecting element 1020 isarranged between the positive terminal 112 and the switching unit 230.More specifically, the one end of the current detecting element 1020 iselectrically connected to the switching unit 230. The other end of thecurrent detecting element 1020 is electrically connected to the wire 106via the positive terminal 112. Note that the current detecting element1020 may be arranged between the switching unit 230 and the positiveterminal 212 of the electric storage unit 210. Also, the switching unit230 or some of the elements constituting the switching unit 230 may beused as the current detecting element 1020.

The current detecting element 1020 may be an element having an optionalresistance value, and its types are not particularly limited. Forexample, the current detecting element 1020 has an appropriateresistance value corresponding to the maximum allowable current of theelectric storage unit 210. Examples of the current detecting element1020 include a resistor and a Hall sensor. A passive element or anactive element having an appropriate resistance value may be used as theabove described resistor.

In the present embodiment, the module control unit 1040 differs from themodule control unit 240 in that the module control unit 1040 detects thecurrent flowing between the wire 106 and the electric storage unit 210.In the present embodiment, the module control unit 1040 differs from themodule control unit 240 in that the module control unit 1040 controlsthe operation of the switching unit 230 based on (i) the voltage or SOCof the electric storage unit 210 and (ii) the current flowing betweenthe wire 106 and the electric storage unit 210. The module control unit1040 may control the operation of the switching unit 230 based on (i)the voltage or SOC of the electric storage unit 210, (ii) the currentflowing between the wire 106 and the electric storage unit 210, and(iii) the terminal voltage of the switching unit 230. With respect tothe configuration other than the above described differences, the modulecontrol unit 1040 may have the features similar to those of thecorresponding configuration of the module control unit 240.

The methods by which the module control unit 1040 detects the currentflowing between the wire 106 and the electric storage unit 210 are notparticularly limited. In the present embodiment, the module control unit1040 acquires the information indicating the terminal voltage of thecurrent detecting element 1020 arranged between the positive terminal112 and the positive terminal 212 and based on the information, detectsthe current flowing between the wire 106 and the electric storage unit210. The module control unit 1040 can thereby monitor the currentflowing between the wire 106 and the electric storage unit 210. Themodule control unit 1040 may decide the magnitude of the current flowingbetween the wire 106 and the electric storage unit 210 and also decidethe direction of the above described current.

In an embodiment, if the switching unit 230 adjusts or controls at leastthe magnitude of the current flowing between the wire 106 and theelectric storage unit 210 in the discharge direction, the module controlunit 1040 monitors or detects the current flowing between the wire 106and the electric storage unit 210 in the charge direction. The modulecontrol unit 1040 may monitor or detect the current flowing between thewire 106 and the electric storage unit 210 if the switching unit 230disconnects the electrical connection between the wire 106 and theelectric storage unit 210 in the discharge direction (in some cases,referred to as electrically disconnected in the discharge direction).Note that, in this case, the current detected by the module control unit1040 is consequently the current flowing between the wire 106 and theelectric storage unit 210 in the charge direction.

In another embodiment, if the switching unit 230 adjusts or controls atleast the magnitude of the current flowing between the wire 106 and theelectric storage unit 210 in the charge direction, the module controlunit 1040 monitors or detects the current flowing between the wire 106and the electric storage unit 210 in the discharge direction. The modulecontrol unit 1040 may monitor or detect the current flowing between thewire 106 and the electric storage unit 210 if the switching unit 230disconnects the electrical connection between the wire 106 and theelectric storage unit 210 in the charge direction (in some cases,referred to as electrically disconnected in the charge direction). Notethat, in this case, the current detected by the module control unit 1040is consequently the current flowing between the wire 106 and theelectric storage unit 210 in the discharge direction.

The methods by which the module control unit 1040 controls the operationof the switching unit 230 are not particularly limited. As describedabove, the module control unit 1040 detects the current flowing betweenthe wire 106 and the electric storage unit 210. The module control unit1040 may control the operation of the switching unit 230 based on theinformation indicating the current flowing between the wire 106 and theelectric storage unit 210. The interlock of the switching unit 230 canthereby be safely released when the electric storage module 1010 ishot-swapped.

Similarly to the module control unit 240, the module control unit 1040may acquire the information indicating the terminal voltage of theswitching unit 230. The module control unit 1040 may control theoperation of the switching unit 230 based on the information indicatingthe terminal voltage of the switching unit 230. The time required tohot-swap the electric storage module 1010 is thereby shortened.

Similarly to the module control unit 240, the module control unit 1040may acquire from the protecting unit 250 the information acquired orgenerated by the protecting unit 250. For example, the module controlunit 1040 acquires from the protecting unit 250 information such asinformation indicating that the function of protection againstovercharge is enabled, information indicating that the function ofprotection against overcharge is not enabled, information indicatingthat function of protection against over discharge is enabled, andinformation indicating that the function of protection against overdischarge is not enabled. The module control unit 1040 may control theoperation of the switching unit 230 based on the information acquired orgenerated by the protecting unit 250. The switching unit 230 can therebybe appropriately controlled depending on the state of the electricstorage unit 210.

For example, if the voltage or SOC of the electric storage unit 210 islower than the threshold for the protection against over discharge orequal to or lower than the threshold, the function of protection againstover discharge becomes enabled. If the voltage or SOC of the electricstorage unit 210 is higher than the threshold for the protection againstover discharge or equal to or higher than the threshold, the function ofprotection against over discharge becomes disabled. Also, for example,the voltage or SOC of the electric storage unit 210 is higher than thethreshold for the protection against overcharge or equal to or higherthan the threshold, the function of protection against overchargebecomes enabled. If the voltage or SOC of the electric storage unit 210is lower than the threshold for the protection against overcharge orequal to or lower than the threshold, the function of protection againstovercharge becomes disabled.

Similarly to the module control unit 240, the module control unit 1040may acquire from the system control unit 140 the information acquired orgenerated by the system control unit 140. For example, the modulecontrol unit 1040 acquires from the system control unit 140 theinformation indicating the battery characteristic of the electricstorage unit 210. The module control unit 1040 may control the operationof the switching unit 230 based on the information acquired or generatedby the system control unit 140. The switching unit 230 can thereby beappropriately controlled depending on the state of the electric storageunit 210.

Specific Examples of the Procedure for Controlling the Operation of theSwitching Unit 230

In an embodiment, the module control unit 1040 controls the operation ofthe switching unit 230 based on the state of charge of the electricstorage unit 210. In another embodiment, the module control unit 1040controls the operation of the switching unit 230 based on the terminalvoltage of the switching unit 230. In still another embodiment, themodule control unit 1040 controls the operation of the switching unit230 based on the current flowing between the wire 106 and the electricstorage unit 210. The module control unit 1040 may control the operationof the switching unit 230 based on at least one of the magnitude and thedirection of the above described current.

More specifically, the module control unit 1040 controls the operationof the switching unit 230 based on (i) the voltage or SOC of theelectric storage unit 210 and (ii) the current flowing between the wire106 and the electric storage unit 210. The module control unit 1040 maycontrol the operation of the switching unit 230 based on (i) the voltageor SOC of the electric storage unit 210, (ii) the current flowingbetween the wire 106 and the electric storage unit 210, and (iii) theterminal voltage of the switching unit 230.

For example, if the voltage or SOC of the electric storage unit 210satisfies the predetermined condition, the module control unit 1040controls the switching unit 230 such that the switching unit 230electrically connects the wire 106 and the electric storage unit 210.The voltage or SOC of the electric storage unit 210 may be an example ofthe battery characteristic of the electric storage unit 210. Thepredetermined condition may be a condition using a predeterminednumerical range or threshold or may be a condition using a numericalrange or threshold calculated in accordance with a predeterminedprocedure. The deterioration or damage of the electric storage unit 210due to the overcharge or over discharge can thereby be prevented, forexample.

The predetermined condition may be a condition for protecting theelectric storage unit 210. Examples of the predetermined conditioninclude (i) a condition indicating that the voltage or SOC of theelectric storage unit 210 is within a particular numerical range, (ii) acondition indicating that the voltage or SOC of the electric storageunit 210 is higher than a particular threshold or is equal to or higherthan the particular threshold, (iii) a condition indicating that thevoltage or SOC of the electric storage unit 210 is lower than aparticular threshold or is equal to or lower than the particularthreshold, and (v) a condition formed by combination of theseconditions.

The condition indicating that the voltage or SOC of the electric storageunit 210 is within the particular numerical range may be a conditionindicating that at least one of a function of protection againstovervoltage and the function of protection against over discharge of theelectric storage module 1010 is not enabled. The condition indicatingthat the voltage or SOC of the electric storage unit 210 is within theparticular numerical range may be a condition indicating that thefunction of protection against overvoltage and the function ofprotection against over discharge of the electric storage module 1010 isnot enabled. The condition indicating that the voltage or SOC of theelectric storage unit 210 is higher than the particular threshold or isequal to or higher than the particular threshold may be a conditionindicating that the function of protection against over discharge of theelectric storage module 1010 is not enabled. The condition indicatingthat the voltage or SOC of the electric storage unit 210 is lower thanthe particular threshold or is equal to or lower than the particularthreshold may be a condition indicating that the function of protectionagainst overcharge of the electric storage module 1010 is not enabled.

According to the present embodiment, the module control unit 1040controls the switching unit 230 such that the switching unit 230electrically connects the electric storage unit 210 and the wire 106 ifthe terminal voltage of the switching unit 230 satisfies a predeterminedcondition. More specifically, if the difference between the voltage ofthe wire 106 and the voltage of the electric storage unit 210 isrelatively large, the electric storage unit 210 and the wire 106 areelectrically disconnected. On the other hand, if the above describeddifference is relatively small, the electric storage unit 210 and thewire 106 are electrically connected. The rapid hot-swap thereby becomespossible.

The predetermined condition may be a condition for realizing the rapidhot-swap. Examples of the predetermined condition include (i) acondition indicating that the terminal voltage of the switching unit 230is within a particular numerical range, (ii) a condition indicating thatthe terminal voltage of the switching unit 230 is higher than aparticular threshold or is equal to or higher than the particularthreshold, (iii) a condition indicating that the terminal voltage of theswitching unit 230 is lower than a particular threshold or is equal toor lower than the particular threshold, and (v) a condition formed bycombination of these conditions.

Specific Examples of the Procedure for Releasing the Interlock of theProtection Against Over Discharge

If the voltage or SOC of the electric storage unit 210, for example,becomes lower than the threshold for the protection against overdischarge when the electric storage system 100 is discharged, with theelectric storage unit 210 of the electric storage module 1010electrically connected to the wire 106 of the electric storage system100, the protecting unit 250 transmits to the module control unit 1040 asignal for enabling the function of protection against over discharge.At this time, the current flows between the wire 106 and the electricstorage unit 210 in the discharge direction. In this case, the dischargedirection may be an example of a first direction. Also, the chargedirection may be an example of a second direction. Note that, in thepresent embodiment, the discharge direction and the charge direction areopposite to each other.

The case in which the voltage or SOC of the electric storage unit 210 islower than the threshold for the protection against over discharge maybe an example of the case in which the condition for protecting theelectric storage unit 210 is not satisfied. In another embodiment, theprotecting unit 250 may transmit to the module control unit 1040 thesignal for enabling the function of protection against over discharge ifthe voltage or SOC of the electric storage unit 210 is equal to or lowerthan the threshold for the protection against over discharge.

Upon receiving the above described signal, the module control unit 1040controls the switching unit 230 and electrically disconnects the wire106 and the electric storage unit 210. If the electric storage system100 continues being discharged also after the wire 106 and the electricstorage unit 210 are electrically disconnected, the voltage differentialwill be caused between the wire 106 and the electric storage unit 210.

After the discharge of the electric storage system 100 ends, and then,when the charge of the electric storage system 100 is started, a voltagedifferential is caused between the wire 106 and the electric storageunit 210. In this case, when an absolute value of the above describedvoltage differential is higher than the threshold for realizing therapid hot-swap, the module control unit 1040 judges that the terminalvoltage of the switching unit 230 does not satisfy the condition forrealizing the rapid hot-swap. As a result, the charge of the electricstorage system 100 proceeds, with the electric storage unit 210 of theelectric storage module 1010 and the wire 106 of the electric storagesystem 100 electrically disconnected.

On the other hand, (i) when the absolute value of the above describedvoltage differential at the time of starting the charge of the electricstorage system 100 is lower than the threshold for realizing the rapidhot-swap or equal to or lower than the threshold, or (ii) when thecharge of the electric storage system 100 proceeds, and the absolutevalue of the above described voltage differential has become lower thanthe threshold for realizing the rapid hot-swap or becomes equal to orlower than the threshold, the module control unit 1040 controls theswitching unit 230 in an attempt to electrically connect the wire 106and the electric storage unit 210. However, at this stage, the voltageor SOC of the electric storage unit 210 is lower than the threshold forthe protection against over discharge. Because of this, the interlockmechanism of the module control unit 1040 is actuated. As a result, themodule control unit 1040 is unable to control the switching unit 230 andto electrically connect the wire 106 and the electric storage unit 210.

In order for the module control unit 1040 to control the switching unit230 and electrically connect the wire 106 and the electric storage unit210, the above described interlock needs to be released by some logic.Although the method for releasing the above described interlock is notparticularly limited, in the present embodiment, the module control unit1040 decides whether or not to release the above described interlock,based on the current flowing between the wire 106 and the electricstorage unit 210 or based on the information related to the current, andcontrols the operation of the switching unit 230.

Here, as described in association with FIG. 5, the switching unit 230includes the transistor 520 that adjusts or controls the magnitude ofthe current flowing between the wire 106 and the electric storage unit210 in the discharge direction. Examples of the transistor 520 include aSi-MOSFET, an insulated gate bipolar transistor (IGBT), a SiC-MOSFET,and a GaN-MOSFET.

If the rated voltage of the electric storage unit 210 is relativelyhigh, the transistor 520 is preferably a SiC-MOSFET. For example, if themaximum value of the rated voltage of the electric storage unit 210 isequal to or higher than 100 V, preferably equal to or higher than 200 V,more preferably equal to or higher than 300 V, and is further morepreferably equal to or higher than 500 V, and still more preferablyequal to or higher than 800 V, and is even further more preferably 1000V, a SiC-MOSFET is used as the transistor 520. The advantage of theSiC-MOSFET, namely having the superior breakdown voltage characteristicsbut allowing little loss, can thereby be sufficiently demonstrated. Ifthe maximum value of the rated voltage of the electric storage unit 210is equal to or higher than 300 V or equal to or higher than 500 V, theeffect of using the SiC-MOSFET as the transistor 520 may becomesignificant.

Also, a parasitic diode is formed between the source and drain of thetransistor 520. The above described parasitic diode allows the passageof the current flowing between the wire 106 and the electric storageunit 210 in the charge direction. On the other hand, the above describedparasitic diode suppresses the flow of the current between the wire 106and the electric storage unit 210 in the discharge direction via theparasitic diode.

The transistor 520 may be an example of the first current adjusting unitor the second current adjusting unit. The parasitic diode of thetransistor 520 may be an example of a first bypass unit or a secondbypass unit. Note that, apart from the parasitic diode of the transistor520, the switching unit 230 may include a rectifier that has a functionsimilar to that of the parasitic diode and is connected in parallel withthe transistor 520 between the wire 106 and the electric storage unit210. Examples of the above described rectifier include (i) a rectifyingelement such as a diode and (ii) a rectifying circuit configured with aplurality of elements.

As described above, according to the present embodiment, the switchingunit 230 includes (i) the transistor 520 that adjusts the current in thedischarge direction and (ii) the parasitic diode that is arranged inparallel with the transistor 520 and that allows the passage of thecurrent in the charge direction but does not allow the passage of thecurrent in the discharge direction. Because of this, when the charge ofthe electric storage system 100 further proceeds, and the voltage of thewire 106 becomes higher than the voltage of the positive terminal 212 ofthe electric storage unit 210, the current starts flowing between thewire 106 and the electric storage unit 210 in the charge direction viathe parasitic diode of the transistor 520.

If the deterioration or damage of the electric storage unit 210 due toover discharge is to be prevented, the module control unit 1040 needs toprevent the flow of the current in the discharge direction but may notneed to prevent the flow of the current in the charge direction. Here,according to the present embodiment, the module control unit 1040monitors the current flowing between the wire 106 and the electricstorage unit 210.

In an embodiment, the module control unit 1040 detects the currentflowing between the wire 106 and the electric storage unit 210 in thecharge direction. In another embodiment, the module control unit 1040may detect the current flowing between the wire 106 and the electricstorage unit 210 when the switching unit 230 electrically disconnectsthe wire 106 and the electric storage unit 210 in the dischargedirection.

After the charge of the electric storage system 100 is started and untilthe above described current is detected, the module control unit 1040maintains the interlock for the protection against over discharge. Onthe other hand, if the above described current has been detected, themodule control unit 1040 releases the interlock for the protectionagainst over discharge.

In an embodiment, the module control unit 1040 controls the switchingunit 230 and electrically connects the wire 106 and the electric storageunit 210. In general, because the value of the ON-resistance of thetransistor 520 is lower than the resistance value of the parasiticdiode, according to the present embodiment, the charge and dischargeefficiency of the electric storage unit 210 is improved.

If the above described current has been detected in the state that theabove described voltage differential does not satisfy the condition forrealizing the rapid hot-swap, the module control unit 1040 may controlthe switching unit 230 such that the switching unit 230 electricallyconnects the wire 106 and the electric storage unit 210 at least untilthe above described voltage differential satisfies the condition forrealizing the rapid hot-swap. Note that while the above describedvoltage differential satisfies the condition for realizing the rapidhot-swap, the module control unit 1040 may control the switching unit230 such that the switching unit 230 electrically connects the wire 106and the electric storage unit 210.

In another embodiment, if the above described current has been detected,the module control unit 1040 may transmit to the protecting unit 250 asignal for resetting the function of protection against over discharge.Then, upon receiving the signal for resetting the function of protectionagainst over discharge, the protecting unit 250 may control theswitching unit 230 and electrically connect the wire 106 and theelectric storage unit 210.

If the charge of the electric storage system 100 further proceeds afterthe wire 106 and the electric storage unit 210 are electricallyconnected, the voltage or SOC of the electric storage unit 210 becomeshigher than the threshold for the protection against over discharge. Ifthe voltage or SOC of the electric storage unit 210 has become higherthan the threshold for the protection against over discharge, theprotecting unit 250 may transmit to the module control unit 1040 asignal for resetting the function of protection against over discharge.Upon receiving the signal for resetting the function of protectionagainst over discharge, the module control unit 1040 may control theswitching unit 230 such that the switching unit 230 electricallyconnects the electric storage unit 210 and the wire 106.

Note that, as described above, if it has been decided that the functionof protection against over discharge is to be enabled, the modulecontrol unit 1040, for example, (i) electrically disconnects the wire106 and the electric storage unit 210 or (ii) reduces the magnitude ofthe current that may flow between the wire 106 and the electric storageunit 210 in the discharge direction. If the function of protectionagainst over discharge is enabled, the magnitude of the current that mayflow in the discharge direction thereby becomes smaller than in a casein which the function of protection against over discharge is disabled.On the other hand, if it has been decided that the interlock of theprotection against over discharge is to be released (in some cases,referred to as disabling the function of protection against overdischarge), the module control unit 1040, for example, (i) electricallyconnects the wire 106 and the electric storage unit 210 or (ii)increases the magnitude of the current that may flow between the wire106 and the electric storage unit 210 in the discharge direction.

The module control unit 1040 adjusts or controls the magnitude of thecurrent flowing between the wire 106 and the electric storage unit 210in the discharge direction by adjusting the resistance value or theconduction ratio (in some cases, referred to as duty ratio) of theswitching unit 230. In an embodiment, if the switching unit 230 includesthe transistor 520, and the transistor 520 is a field effect transistor,the module control unit 1040 can adjust or control the magnitude of thecurrent flowing between the wire 106 and the electric storage unit 210in the discharge direction by adjusting the gate voltage of thetransistor 520 (in some cases, referred to as input voltage). The modulecontrol unit 1040 may adjust or control the magnitude of the currentflowing between the wire 106 and the electric storage unit 210 in thedischarge direction by controlling the operation of the element(s)arranged in a circuit for adjusting the input voltage of the transistor520.

In another embodiment, if the switching unit 230 includes the transistor520, and the transistor 520 is a bipolar transistor, the module controlunit 1040 can adjust or control the magnitude of the current flowingbetween the wire 106 and the electric storage unit 210 in the dischargedirection by adjusting the base current of the transistor 520 (in somecases, referred to as input current). The module control unit 1040 mayadjust or control the magnitude of the current flowing between the wire106 and the electric storage unit 210 in the discharge direction bycontrolling the operation of the element(s) arranged in the circuit foradjusting the input current of the transistor 520.

The resistance value or conduction ratio of the switching unit 230 in acase in which the function of protection against over discharge isenabled and the resistance value or conduction ratio of the switchingunit 230 in a case in which the function of protection against overdischarge is disabled may be the same or different. If the switchingunit 230 has a switching element, the ON-resistance of the switchingelement in a case in which the function of protection against overchargeis enabled and the ON-resistance of the switching element in a case inwhich the function of protection against overcharge is disabled may bethe same or different. If the switching unit 230 has a variableresistor, the resistance value of the variable resistor in the case inwhich the function of protection against overcharge is enabled and theresistance value of the variable resistor in the case in which thefunction of protection against overcharge is disabled may be the same ordifferent. If the function of protection against over discharge isenabled, the module control unit 1040 may control the switching unit 230such that the resistance value of the switching unit 230 becomes higherthan in the case in which the function of protection against overdischarge is disabled. If the function of protection against overdischarge is enabled, the module control unit 1040 may control theswitching unit 230 such that the conduction ratio of the switching unit230 becomes lower than in the case in which the function of protectionagainst over discharge is disabled.

The above in the present embodiment has described, in order to simplifythe description, a procedure in which the module control unit 1040releases the interlock of the protection against over discharge,illustrating as an example the embodiment in which (i) if it has beendecided that the function of protection against over discharge is to beenabled, the module control unit 1040 electrically disconnects the wire106 and the electric storage unit 210 and (ii) if it has been decidedthat the function of protection against over discharge is to bedisabled, the module control unit 1040 electrically connects the wire106 and the electric storage unit 210. However, it should be understoodby the person skilled in the art who has accessed the description of thepresent specification, that the module control unit 1040 may release theinterlock of the protection against over discharge in a proceduresimilar to that of the present embodiment also in another embodiment inwhich (i) if it has been decided that the function of protection againstover discharge is to be enabled, the module control unit 1040 reducesthe magnitude of the current that may flow between the wire 106 and theelectric storage unit 210 in the discharge direction and (ii) if it hasbeen decided that the function of protection against over discharge isto be disabled, the module control unit 1040 increases the magnitude ofthe current that may flow between the wire 106 and the electric storageunit 210 in the discharge direction.

Specifically, if the function of protection against over discharge is tobe enabled, in the present embodiment, a series of operation of themodule control unit 1040 for electrically disconnecting the wire 106 andthe electric storage unit 210 corresponds to a series of operation ofthe module control unit 1040 for reducing the current that may flowbetween the electric storage unit 210 and the wire 106 in the abovedescribed another embodiment. Similarly, if the function of protectionagainst over discharge is to be disabled, in the present embodiment, aseries of operation of the module control unit 1040 for electricallyconnecting the wire 106 and the electric storage unit 210 corresponds toa series of operation of the module control unit 1040 for increasing thecurrent that may flow between the electric storage unit 210 and the wire106 in the above described another embodiment.

Specific Examples of the Procedure for Releasing the Interlock of theProtection Against Overcharge

If the voltage or SOC of the electric storage unit 210, for example,becomes higher than the threshold for the protection against overchargewhen the electric storage system 100 is charged, with the electricstorage unit 210 of the electric storage module 1010 electricallyconnected to the wire 106 of the electric storage system 100, theprotecting unit 250 transmits to the module control unit 1040 a signalfor enabling the function of protection against overcharge. At thistime, the current flows between the wire 106 and the electric storageunit 210 in the charge direction. In this case, the charge direction maybe an example of the first direction. Also, the discharge direction maybe an example of the second direction. Note that, in the presentembodiment, the discharge direction and the charge direction areopposite to each other.

The case in which the voltage or SOC of the electric storage unit 210 ishigher than the threshold for the protection against overcharge may bean example of the case in which the condition for protecting theelectric storage unit 210 is not satisfied. In another embodiment, theprotecting unit 250 may transmit to the module control unit 1040 thesignal for enabling the function of protection against overcharge if thevoltage or SOC of the electric storage unit 210 is equal to or higherthan the threshold for the protection against over discharge.

Upon receiving the above described signal, the module control unit 1040controls the switching unit 230 and electrically disconnects the wire106 and the electric storage unit 210. If the electric storage system100 continues being charged also after the wire 106 and the electricstorage unit 210 are electrically disconnected, a voltage differentialwill be caused between the wire 106 and the electric storage unit 210.

After the charge of the electric storage system 100 ends, and then whenthe discharge of the electric storage system 100 is started, a voltagedifferential is caused between the wire 106 and the electric storageunit 210. In this case, when an absolute value of the above describedvoltage differential is higher than the threshold for realizing therapid hot-swap, the module control unit 1040 judges that the terminalvoltage of the switching unit 230 does not satisfy the condition forrealizing the rapid hot-swap. As a result, the discharge of the electricstorage system 100 proceeds, with the electric storage unit 210 of theelectric storage module 1010 and the wire 106 of the electric storagesystem 100 electrically disconnected.

On the other hand, (i) when the absolute value of the above describedvoltage differential at the time of starting the discharge of theelectric storage system 100 is lower than the threshold for realizingthe rapid hot-swap or equal to or lower than the threshold, or (ii) whenthe charge of the electric storage system 100 proceeds, and the absolutevalue of the above described voltage differential has become lower thanthe threshold for realizing the rapid hot-swap or becomes equal to orlower than the threshold, the module control unit 1040 controls theswitching unit 230 in an attempt to electrically connect the wire 106and the electric storage unit 210. However, at this stage, the voltageor SOC of the electric storage unit 210 is higher than the threshold forthe protection against overcharge. Because of this, the interlockmechanism of the module control unit 1040 is actuated. As a result, themodule control unit 1040 is unable to control the switching unit 230 andto electrically connect the wire 106 and the electric storage unit 210.

In order for the module control unit 1040 to control the switching unit230 and electrically connect the wire 106 and the electric storage unit210, the above described interlock needs to be released by some logic.Although the method for releasing the above described interlock is notparticularly limited, in the present embodiment, the module control unit1040 decides whether or not to release the above described interlock,based on the current flowing between the wire 106 and the electricstorage unit 210 or based on the information related to the current, andcontrols the operation of the switching unit 230.

Here, as described in association with FIG. 5, the switching unit 230includes the transistor 510 that adjusts or controls the magnitude ofthe current flowing between the wire 106 and the electric storage unit210 in the charge direction. Examples of the transistor 510 include aSi-MOSFET, an insulated gate bipolar transistor (IGBT), a SiC-MOSFET,and a GaN-MOSFET.

If the rated voltage of the electric storage unit 210 is relativelyhigh, the transistor 510 is preferably a SiC-MOSFET. For example, if themaximum value of the rated voltage of the electric storage unit 210 isequal to or higher than 100 V, preferably equal to or higher than 200 V,more preferably equal to or higher than 300 V, further more preferablyequal to or higher than 500 V, still further more preferably equal to orhigher than 800 V, and is even further more preferably 1000 V, aSiC-MOSFET is used as the transistor 510. The advantage of theSiC-MOSFET, namely having the superior breakdown voltage characteristicsbut allowing little loss, can thereby be sufficiently demonstrated. Ifthe maximum value of the rated voltage of the electric storage unit 210is equal to or higher than 300 V or equal to or higher than 500 V, theeffect of using the SiC-MOSFET as the transistor 510 may becomesignificant.

Also, a parasitic diode is formed between the source and drain of thetransistor 510. The above described parasitic diode allows the passageof the current flowing between the wire 106 and the electric storageunit 210 in the discharge direction. On the other hand, the abovedescribed parasitic diode suppresses the flow of the current between thewire 106 and the electric storage unit 210 in the charge direction viathe parasitic diode.

The transistor 510 may be an example of the first current adjusting unitor the second current adjusting unit. The parasitic diode of thetransistor 510 may be an example of the first bypass unit or the secondbypass unit. Note that, apart from the parasitic diode of the transistor510, the switching unit 230 may include a rectifier that has a functionsimilar to that of the parasitic diode and is connected in parallel withthe transistor 510 between the wire 106 and the electric storage unit210. Examples of the above described rectifier include (i) a rectifyingelement such as a diode and (ii) a rectifying circuit configured with aplurality of elements.

As described above, according to the present embodiment, the switchingunit 230 includes (i) the transistor 510 that adjusts the current in thecharge direction and (ii) the parasitic diode that is arranged inparallel with the transistor 510 and that allows the passage of thecurrent in the discharge direction but does not allow the passage of thecurrent in the charge direction. Because of this, when the discharge ofthe electric storage system 100 further proceeds, and the voltage of thewire 106 becomes lower than the voltage of the positive terminal 212 ofthe electric storage unit 210, the current starts flowing between thewire 106 and the electric storage unit 210 in the discharge directionvia the parasitic diode of transistor 510.

If the deterioration or damage of the electric storage unit 210 due tothe overcharge is to be prevented, the module control unit 1040 needs toprevent the flow of the current in the charge direction but may not needto prevent the flow of the current in the discharge direction. Here,according to the present embodiment, the module control unit 1040monitors the current flowing between the wire 106 and the electricstorage unit 210.

In an embodiment, the module control unit 1040 detects the currentflowing between the wire 106 and the electric storage unit 210 in thedischarge direction. In another embodiment, the module control unit 1040may detect the current flowing between the wire 106 and the electricstorage unit 210 when the switching unit 230 electrically disconnectsthe wire 106 and the electric storage unit 210 in the charge direction.

After the discharge of the electric storage system 100 is started anduntil the above described current has been detected, the module controlunit 1040 maintains the interlock for the protection against overcharge.On the other hand, if the above described current has been detected, themodule control unit 1040 releases the interlock for the protectionagainst overcharge.

In an embodiment, the module control unit 1040 controls the switchingunit 230 and electrically connect the wire 106 and the electric storageunit 210. In general, because the value of the ON-resistance of thetransistor 510 is lower than the resistance value of the parasiticdiode, according to the present embodiment, the charge and dischargeefficiency of the electric storage unit 210 is improved.

If the above described current has been detected in the state that theabove described voltage differential does not satisfy the condition forrealizing the rapid hot-swap, the module control unit 1040 may controlthe switching unit 230 such that the switching unit 230 electricallyconnects the wire 106 and the electric storage unit 210 at least untilthe above described voltage differential satisfies the condition forrealizing the rapid hot-swap. Note that, while the above describedvoltage differential satisfies the condition for realizing the rapidhot-swap, the module control unit 1040 may control the switching unit230 such that the switching unit 230 electrically connects the wire 106and the electric storage unit 210.

In another embodiment, if the above described current has been detected,the module control unit 1040 may transmit to the protecting unit 250 asignal for resetting the function of protection against overcharge.Then, upon receiving the signal for resetting the function of protectionagainst overcharge, the protecting unit 250 may control the switchingunit 230 and electrically connect the wire 106 and the electric storageunit 210.

If the discharge of the electric storage system 100 further proceedsafter the wire 106 and the electric storage unit 210 has beenelectrically connected, the voltage or SOC of the electric storage unit210 becomes lower than the threshold for the protection againstovercharge. If the voltage or SOC of the electric storage unit 210 hasbecome lower than the threshold for the protection against overcharge,the protecting unit 250 may transmit to the module control unit 1040 asignal for resetting the function of protection against overcharge. Uponreceiving the signal for resetting the function of protection againstovercharge, the module control unit 1040 may control the switching unit230 such that the switching unit 230 electrically connects the electricstorage unit 210 and the wire 106.

Note that, as described above, if it has been decided that the functionof protection against overcharge is to be enabled, the module controlunit 1040, for example, (i) electrically disconnects the wire 106 andthe electric storage unit 210 or (ii) reduces the magnitude of thecurrent that may flow between the wire 106 and the electric storage unit210 in the charge direction. If the function of protection againstovercharge is enabled, the magnitude of the current that may flow in thecharge direction thereby becomes smaller than in a case in which thefunction of protection against overcharge is disabled. On the otherhand, if it has been decided that the interlock of the protectionagainst overcharge is to be released (in some cases, referred to asdisabling the function of protection against overcharge), the modulecontrol unit 1040, for example, (i) electrically connects the wire 106and the electric storage unit 210 or (ii) increases the magnitude of thecurrent that may flow between the wire 106 and the electric storage unit210 in the charge direction.

The module control unit 1040 adjusts or controls the magnitude of thecurrent flowing between the wire 106 and the electric storage unit 210in the charge direction by adjusting the resistance value or theconduction ratio of the switching unit 230 (in some cases, referred toas duty ratio). In an embodiment, if the switching unit 230 includes thetransistor 510, and the transistor 510 is a field effect transistor, themodule control unit 1040 can adjust or control the magnitude of thecurrent flowing between the wire 106 and the electric storage unit 210in the charge direction by adjusting the gate voltage of the transistor510 (in some cases, referred to as input voltage). The module controlunit 1040 may adjust or control the magnitude of the current flowingbetween the wire 106 and the electric storage unit 210 in the chargedirection by controlling the operation of the element(s) arranged in acircuit for adjusting the input voltage of the transistor 510.

In another embodiment, if the switching unit 230 includes the transistor510, and the transistor 510 is a bipolar transistor, the module controlunit 1040 can adjust or control the magnitude of the current flowingbetween the wire 106 and the electric storage unit 210 in the chargedirection by adjusting the base current of the transistor 510 (in somecases, referred to as input current). The module control unit 1040 mayadjust or control the magnitude of the current flowing between the wire106 and the electric storage unit 210 in the charge direction bycontrolling the operation of the element(s) arranged in a circuit foradjusting the input current of the transistor 510.

The resistance value or conduction ratio of the switching unit 230 in acase in which the function of protection against overcharge is enabledand the resistance value or conduction ratio of the switching unit 230in a case in which the function of protection against overcharge isdisabled may be the same or different. If the switching unit 230 has aswitching element, the ON-resistance of the switching element in thecase in which the function of protection against overcharge is enabledand the ON-resistance of the switching element in the case in which thefunction of protection against overcharge is disabled may be the same ordifferent. If the switching unit 230 has a variable resistor, theresistance value of the variable resistor in the case in which thefunction of protection against overcharge is enabled and the resistancevalue of the variable resistor in the case in which the function ofprotection against overcharge is disabled may be the same or different.If the function of protection against overcharge is enabled, the modulecontrol unit 1040 may control the switching unit 230 such that theresistance value of the switching unit 230 becomes higher than in thecase in which the function of protection against overcharge is disabled.If the function of protection against overcharge is enabled, the modulecontrol unit 1040 may control the switching unit 230 such that theconduction ratio of the switching unit 230 becomes lower than in thecase in which the function of protection against overcharge is disabled.

The above in the present embodiment has described, in order to simplifythe description, a procedure in which the module control unit 1040releases the interlock of the protection against overcharge,illustrating as an example the embodiment in which (i) if it has beendecided that the function of protection against overcharge is to beenabled, the module control unit 1040 electrically disconnects the wire106 and the electric storage unit 210 and (ii) if it has been decidedthat the function of protection against overcharge is to be disabled,the module control unit 1040 electrically connects the wire 106 and theelectric storage unit 210. However, it should be understood by theperson skilled in the art who has accessed the description of thepresent specification, that the module control unit 1040 may release theinterlock of the protection against overcharge in a procedure similar tothat of the present embodiment also in another embodiment in which (i)if it has been decided that the function of protection againstovercharge is to be enabled, the module control unit 1040 reduces themagnitude of the current that may flow between the wire 106 and theelectric storage unit 210 in the charge direction and (ii) if it hasbeen decided that the function of protection against overcharge is to bedisabled, the module control unit 1040 increases the magnitude of thecurrent that may flow between the wire 106 and the electric storage unit210 in the charge direction.

Specifically, if the function of protection against overcharge is to beenabled, in the present embodiment, a series of operation of the modulecontrol unit 1040 for electrically disconnecting the wire 106 and theelectric storage unit 210 corresponds to a series of operation of themodule control unit 1040 for reducing the current that may flow betweenthe electric storage unit 210 and the wire 106 in the above describedanother embodiment. Similarly, if the function of protection againstovercharge is to be disabled, in the present embodiment, a series ofoperation of the module control unit 1040 for electrically connectingthe wire 106 and the electric storage unit 210 corresponds to a seriesof operation of the module control unit 1040 for increasing the currentthat may flow between the electric storage unit 210 and the wire 106 inthe above described another embodiment.

As described above, according to the present embodiment, the modulecontrol unit 1040 can establish, for example, both the hot-swap functionand the protection function of the electric storage unit 210 withoutsignificantly decrease the charge and discharge efficiency of theelectric storage module 1010.

As described in association with FIG. 1, with respect to an electricstorage module constituting part of a power supply for a small-scalesystem such as a household electric appliance, the number of electricstorage cells connected in series is small, and also, the rated voltagethereof is approximately from 3.5 to 4.5 V. Because of this, if theelectric storage module is implemented in a power supply or an electricstorage module is detached from the power supply, with the systemoperating, it may be required to strictly manage the voltage of theelectric storage module targeted for hot-swap and the voltage of theother electric storage module(s) constituting the power supply.Depending on the specification of the electric storage module, thetolerance for the voltage differential between the electric storagemodule targeted for hot-swap and the other electric storage module(s)constituting the power supply may be managed to be less than 1 V.

On the other hand, in recent years, enlarging the size of the electricstorage modules has been advanced. For example, in small to mid sizeelectric vehicles such as passenger cars, electric storage moduleshaving the rated voltage of approximately from 300 to 400 V are used.Also, in large size electric vehicles such as electric buses, electricstorage modules having the rated voltage of approximately from 500 to800 V have come into use. As the rated voltage of an electric storagemodule becomes higher, the tolerance for the voltage differentialbetween the electric storage module targeted for hot-swap and the otherelectric storage module(s) constituting the power supply becomes higher.For example, even if the voltage differential between one electricstorage module constituting a power supply and the other electricstorage module(s) constituting the power supply exceeds 1 V, the oneelectric storage module can be hot-swapped in some cases.

Although depending on the resistance or impedance of the electricstorage module targeted for hot-swap, the voltage differential betweenthe electric storage module targeted for hot-swap and the other electricstorage module(s) constituting the power supply may be equal to or lowerthan 30 V, equal to or lower than 10 V, equal to or lower than 5 V,equal to or lower than 3 V, equal to or lower than 2 V, or equal to orlower than 1 V if the rated voltage of the electric storage moduletargeted for hot-swap is equal to or higher than 100 V. The voltagedifferential between the electric storage module targeted for hot-swapand the other electric storage module(s) constituting the power supplymay be equal to or lower than one fifth, equal to or lower than onetenth, equal to or lower than one twentieth, equal to or lower than onethirtieth, equal to or lower than one fiftieth, equal to or lower thanone hundredth, equal to or lower than one two hundredth, equal to orlower than one three hundredth, equal to or lower than one fivehundredth, or equal to or lower than one thousandth of the rated voltageof the electric storage module targeted for hot-swap.

As described above, in the present embodiment, the current detectingelement 1020 and the switching unit 230 are arranged between thepositive terminal 112 of the electric storage module 1010 and thepositive terminal 212 of the electric storage unit 210, and the positiveterminal 212 of the electric storage unit 210 is electrically connectedto the wire 106 via the switching unit 230. However, the arrangement ofthe current detecting element 1020 and the switching unit 230 is notlimited to the present embodiment. In another embodiment, the currentdetecting element 1020 and the switching unit 230 are arranged betweenthe negative terminal 114 of the electric storage module 1010 and thenegative terminal 214 of the electric storage unit 210, and the negativeterminal 214 of the electric storage unit 210 is electrically connectedto the wire 106 via the switching unit 230.

FIG. 11 schematically shows an example of the system configuration ofthe module control unit 1040. In the present embodiment, the modulecontrol unit 1040 includes the determining unit 310, the receiving unit320, and the signal generating unit 330. The module control unit 1040may also include the module information acquiring unit 340, the moduleinformation storing unit 350, and the module information transmittingunit 360. In the present embodiment, the module control unit 1040includes a current monitoring unit 1120. In the present embodiment, thecurrent monitoring unit 1120 has a current detecting unit 1122 and adirection deciding unit 1124. The signal generating unit 330 may be anexample of an operation control unit.

In the present embodiment, the module control unit 1040 differs from themodule control unit 240 in that the module control unit 1040 includesthe current monitoring unit 1120. With respect to the configurationother than the above described difference, the module control unit 1040may have the features similar to those of the correspondingconfiguration of the module control unit 240.

In the present embodiment, the current monitoring unit 1120 monitors thecurrent flowing between the wire 106 of the electric storage system 100and the electric storage unit 210 of the electric storage module 1010.For example, the current monitoring unit 1120 monitors the currentflowing between the positive terminal 112 and the positive terminal 212of the electric storage module 1010.

In the present embodiment, the current detecting unit 1122 detects thecurrent flowing between the wire 106 of the electric storage system 100and the electric storage unit 210 of the electric storage module 1010.The current detecting unit 1122 may decide the magnitude of the abovedescribed current. The current detecting unit 1122 may be configured byan optional analog circuit or configured by an optional digital circuit.

In the present embodiment, the direction deciding unit 1124 decides thedirection of the current flowing between the wire 106 of the electricstorage system 100 and the electric storage unit 210 of the electricstorage module 1010. The direction deciding unit 1124 may be configuredby an optional analog circuit or configured by an optional digitalcircuit.

FIG. 12 schematically shows an example of the circuit configuration ofthe module control unit 1040. FIG. 12 schematically shows an example ofthe circuit configuration of the switching unit 230. FIG. 12 shows anexample of the switching unit 230 and an example of the module controlunit 1040, together with the positive terminal 112, the negativeterminal 114, the electric storage unit 210, the protecting unit 250,and the current detecting element 1020.

Specific Examples of the Circuit of the Switching Unit 230

In the present embodiment, one end of the transistor 510 is electricallyconnected to the wire 106, and the other end thereof is electricallyconnected to the electric storage unit 210. Between the wire 106 and theelectric storage unit 210, the transistor 510 is connected in serieswith the transistor 520 and the parasitic diode 844. In the presentembodiment, the transistor 510 adjusts the magnitude of the currentflowing between the wire 106 and the electric storage unit 210 in thecharge direction.

In the present embodiment, one end of the transistor 520 is electricallyconnected to the wire 106, and the other end thereof is electricallyconnected to the electric storage unit 210. Between the wire 106 and theelectric storage unit 210, the transistor 520 is connected in serieswith the transistor 510 and the parasitic diode 842. In the presentembodiment, the transistor 520 adjusts the magnitude of the currentflowing between the wire 106 and the electric storage unit 210 in thedischarge direction.

One end of the parasitic diode 842 is electrically connected to the wire106, and other end thereof is electrically connected to the electricstorage unit 210. Between the wire 106 and the electric storage unit210, the parasitic diode 842 is connected in parallel with thetransistor 510. Between the wire 106 and the electric storage unit 210,the parasitic diode 842 is connected in series with the transistor 520and the parasitic diode 844.

The parasitic diode 842 allows the passage of the current flowingbetween the wire 106 and the electric storage unit 210 in the dischargedirection. On the other hand, the parasitic diode 842 suppresses theflow of the current between the wire 106 and the electric storage unit210 in the charge direction via the parasitic diode 842.

One end of the parasitic diode 844 is electrically connected to the wire106, and the other end thereof is electrically connected to the electricstorage unit 210. Between the wire 106 and the electric storage unit210, the parasitic diode 844 is connected in parallel with thetransistor 520. Between the wire 106 and the electric storage unit 210,the parasitic diode 844 is connected in series with the transistor 510and the parasitic diode 842.

The parasitic diode 842 allows the passage of the current flowingbetween the wire 106 and the electric storage unit 210 in the chargedirection. On the other hand, the parasitic diode 844 suppresses theflow of the current between the wire 106 and the electric storage unit210 in the discharge direction via the parasitic diode 844.

The transistor 510 may be an example of one of the first currentadjusting unit and the second current adjusting unit. The transistor 520may be an example of the other one of the first current adjusting unitand the second current adjusting unit. The parasitic diode 842 may be anexample of one of the first bypass unit and the second bypass unit. Theparasitic diode 844 may be an example of the other one of the firstbypass unit and the second bypass unit. The discharge direction may bean example of one of the first direction and the second direction. Thecharge direction may be an example of the other one of the firstdirection and the second direction.

Specific Examples of the Circuit of the Module Control Unit 1040

In the present embodiment, the module control unit 1040 includes thedetermining unit 310, the signal generating unit 330, and the currentmonitoring unit 1120. The determining unit 310 may be an example of afirst deciding unit, a second deciding unit, and a third deciding unit.

In the present embodiment, the signal generating unit 330 includes an ORcircuit 1260, an AND circuit 1272, an AND circuit 1274, an OR circuit1282, and an OR circuit 1284. Also, in the present embodiment, betweenthe positive terminal 112 and the switching unit 230, a resistor havingan appropriate resistance value is arranged as the current detectingelement 1020. The resistance value of the current detecting element 1020is decided, for example, such that the current monitoring unit 1120 cancertainly determine the direction of the current flowing between thewire 106 and the electric storage unit 210.

In the present embodiment, the determining unit 310 determines whetheror not the terminal voltage of the switching unit 230 is within apredetermined range. The determining unit 310 transmits to the signalgenerating unit 330 a signal indicating the determination result. Thedetermining unit 310 may be configured by an optional analog circuit orconfigured by an optional digital circuit. The determining unit 310 mayinclude a window comparator. The window comparator can be realized, forexample, by using two comparators.

In the present embodiment, the determining unit 310 has two inputterminals. To one of the input terminals of the determining unit 310(shown as a −terminal in the drawing), the voltage of one end of theswitching unit 230 (for example, the end on the positive terminal 112side) is input. To the other input terminal of the determining unit 310(shown as a +terminal in the drawing), the voltage of the other end ofthe switching unit 230 (for example, the end on the electric storageunit 210 side) is input.

In the present embodiment, the determining unit 310 has two outputterminals. As a signal indicating the determination result, thedetermining unit 310 outputs from one of the output terminals (shown asL terminal in the drawing) a signal indicating that the terminal voltageof the switching unit 230 is lower than a first threshold. For example,if the terminal voltage of the switching unit 230 is lower than thefirst threshold, the determining unit 310 outputs H logic from the Lterminal. On the other hand, if the terminal voltage of the switchingunit 230 is equal to or higher than the first threshold, the determiningunit 310 outputs L logic from the L terminal.

Also, as a signal indicating the determination result, the determiningunit 310 outputs from the other output terminal (shown as H terminal inthe drawing) a signal indicating that the terminal voltage of theswitching unit 230 is higher than a second threshold. In the presentembodiment, as the absolute value of the second threshold, a valuehigher than the absolute value of the first threshold is set. Forexample, if the terminal voltage of the switching unit 230 is higherthan the second threshold, the determining unit 310 outputs H logic fromthe H terminal. On the other hand, if the terminal voltage of theswitching unit 230 is equal to or lower than the second threshold, thedetermining unit 310 outputs L logic from the H terminal.

In an embodiment, the determining unit 310 can decide, for example,whether or not the voltage or SOC of the electric storage unit 210matches a first condition. Examples of the first condition include (i) acondition indicating that the voltage or SOC of the electric storageunit is outside a predetermined first numerical range, (ii) a conditionindicating that the voltage or SOC of the electric storage unit ishigher than a predetermined first threshold, and (iii) a conditionindicating that the voltage or SOC of the electric storage unit is equalto or higher than the first threshold. The first condition may be acondition indicating that the electric storage unit 210 is overcharged,for example.

In another embodiment, the determining unit 310 can decide, for example,whether or not the voltage or SOC of the electric storage unit 210matches a second condition. Examples of the second condition include (i)a condition indicating that the voltage or SOC of the electric storageunit is outside a predetermined second numerical range, (ii) a conditionindicating that the voltage or SOC of the electric storage unit is lowerthan a predetermined second threshold, and (iii) a condition indicatingthat the voltage or SOC of the electric storage unit is equal to orlower than the second threshold. Note that the second condition may be acondition different from the first condition. The second condition is acondition indicating that the electric storage unit 210 is overdischarged, for example.

In still another embodiment, the determining unit 310 can decide, forexample, whether or not the terminal voltage of the switching unit 230matches a third condition. Examples of the third condition include (i) acondition indicating that the terminal voltage of the switching unit 230is within a predetermined third numerical range, (ii) a conditionindicating that the terminal voltage of the switching unit 230 is lowerthan a predetermined third threshold, and (iii) a condition indicatingthat the terminal voltage of the switching unit 230 is equal to or lowerthan the third threshold.

In still another embodiment, the determining unit 310 can decide, forexample, whether or not the terminal voltage of the switching unit 230matches a fourth condition. Examples of the fourth condition include (i)a condition indicating that the terminal voltage of the switching unit230 is outside a predetermined fourth numerical range, (ii) a conditionindicating that the terminal voltage of the switching unit 230 is higherthan a predetermined fourth threshold, and (iii) a condition indicatingthat the terminal voltage of the switching unit 230 is equal to orhigher than the fourth threshold. The fourth numerical range may be thesame as the third numerical range. The upper limit value in the fourthnumerical range may be higher than the upper limit value in the thirdnumerical range. The fourth threshold may be the same as the thirdthreshold. The fourth threshold may be higher than the third threshold.

In the present embodiment, the current monitoring unit 1120 may includea comparator. The current monitoring unit 1120 has, for example, twoinput terminals and one output terminal. To one of the input terminalsof the current monitoring unit 1120 (shown as a +terminal in thedrawing), the voltage of one end of the current detecting element 1020(for example, the end on the positive terminal 112 side) is input. Tothe other input terminal of the current monitoring unit 1120 (shown as a−terminal in the drawing), the voltage of the other end of the currentdetecting element 1020 (for example, the end on the switching unit 230side) is input.

For example, if the voltage input to the +terminal is higher than thevoltage input to the −terminal, the current monitoring unit 1120 outputsH logic from the output terminal. On the other hand, if the voltageinput to the +terminal is lower than the voltage input to the −terminal,the current monitoring unit 1120 outputs L logic from the outputterminal. Also, if the voltage input to the +terminal and the voltageinput to the −terminal are equal, or if both of the voltages can beregarded as equal, the current monitoring unit 1120 does not output asignal from the output terminal.

In the present embodiment, when at least one of the transistor 510 andthe transistor 520 electrically disconnects the wire 106 and theelectric storage unit 210, the current monitoring unit 1120 detects thecurrent flowing between the wire 106 and the electric storage unit 210.In an embodiment, when the function of protection against overcharge isenabled, the current monitoring unit 1120 detects the current flowingbetween the wire 106 and the electric storage unit 210 in the dischargedirection. In another embodiment, when the function of protectionagainst over discharge is enabled, the current monitoring unit 1120detects the current flowing between the wire 106 and the electricstorage unit 210 in the charge direction.

In the present embodiment, the signal generating unit 330 may also havethe function of the receiving unit 320. For example, the signalgenerating unit 330 receives from the protecting unit 250 the signal 86for enabling the function of protection against over discharge. Also,the signal generating unit 330 receives from the protecting unit 250 thesignal 88 for enabling the function of protection against overcharge.The signal generating unit 330 receives from the determining unit 310information related to the terminal voltage of the switching unit 230.The signal generating unit 330 receives from the current monitoring unit1120 information related to the current between the wire 106 and theelectric storage unit 210.

In the present embodiment, the signal generating unit 330 can controlthe operation of at least one of the transistor 510 and the transistor520 based on (i) voltage or SOC of the electric storage unit 210 and(ii) the detection result of the current monitoring unit 1120. Thesignal generating unit 330 can control the operation of at least one ofthe transistor 510 and the transistor 520 based on (i) the voltage orSOC of the electric storage unit 210, (ii) the detection result of thecurrent monitoring unit 1120, and (iii) the determination result of thedetermining unit 310. The signal generating unit 330 may control atleast one of the transistor 510 and the transistor 520 by outputting asignal for controlling the operation of at least one of the transistor510 and the transistor 520 to the transistor targeted for the control bythe signal.

In the present embodiment, if the determining unit 310 has decided thatthe terminal voltage of the switching unit 230 matches the fourthcondition, the signal generating unit 330 may output to at least one ofthe transistor 510 and the transistor 520 a signal for executing theoperation for electrically disconnecting the wire 106 and the electricstorage unit 210 or the operation for reducing the current flowingbetween the wire 106 and the electric storage unit 210. The determiningunit 310 may thereby be used also as the overcurrent protection functionof the electric storage unit 210.

In the present embodiment, the OR circuit 1260 has two input terminalsand one output terminal. To one of the input terminals of the OR circuit1260, the output from the H terminal of the determining unit 310 isinput. To the other input terminal of the OR circuit 1260, the outputfrom the L terminal of the determining unit 310 is input.

The OR circuit 1260 outputs logical sum (OR) of the two inputs. Forexample, if the terminal voltage of the switching unit 230 stays in aparticular numerical range, the OR circuit 1260 outputs L logic. On theother hand, if the terminal voltage of the switching unit 230 is outsidethe particular numerical range, the OR circuit 1260 outputs the H logic.For example, if the terminal voltage of the switching unit 230 is higherthan a particular value, which is as an example in which the switchingunit 230 matches the above described fourth condition, the H logic isoutput from the H terminal of the determining unit 310. In this case,the OR circuit 1260 outputs the H logic.

In the present embodiment, the AND circuit 1272 has two input terminalsand one output terminal. To one of the input terminals of the ANDcircuit 1272, a signal produced by inverting the output of the ORcircuit 1260 is input. To the other input terminal of the AND circuit1272, a signal produced by inverting the signal 88 for enabling thefunction of protection against overcharge is input.

The AND circuit 1272 outputs logical product (AND) of the two inputs.For example, if the terminal voltage of the switching unit 230 stays ina particular numerical range (specifically, if the absolute value of thedifference between the voltage of the wire 106 and the voltage of theelectric storage unit 210 is lower than a particular threshold or equalto or lower than the threshold), and if the voltage or SOC of theelectric storage unit 210 is lower than the threshold for the protectionagainst overcharge, the AND circuit 1272 outputs the H logic. On theother hand, in the case other than the above, the AND circuit 1272outputs L logic.

In the present embodiment, the AND circuit 1274 has two input terminalsand one output terminal. T one of the input terminals of the AND circuit1274, a signal produced by inverting the output of the OR circuit 1260is input. To the other input terminal of the AND circuit 1274, a signalproduced by inverting the signal 86 for enabling the function ofprotection against over discharge is input.

The AND circuit 1274 outputs logical product (AND) of the two inputs.For example, if the terminal voltage of the switching unit 230 stays ina particular numerical range (specifically, if the absolute value of thedifference between the voltage of the wire 106 and the voltage of theelectric storage unit 210 is lower than a particular threshold or equalto or lower than the particular threshold), and if the voltage or SOC ofthe electric storage unit 210 is higher than the threshold for theprotection against over discharge, the AND circuit 1274 outputs the Hlogic. On the other hand, in the case other than the above, the ANDcircuit 1274 outputs L logic.

In the present embodiment, the OR circuit 1282 has two input terminalsand one output terminal. To one of the input terminals of the OR circuit1282, a signal produced by inverting the output of the currentmonitoring unit 1120 is input. To the other input terminal of the ORcircuit 1282, the output of the AND circuit 1272 is input.

The OR circuit 1282 outputs logical sum (OR) of the two inputs. Forexample, if the output of the OR circuit 1282 is H logic, the transistor510 is turned on, and if the output of the OR circuit 1282 is L logic,the transistor 510 is turned off. In an embodiment, if the current flowsbetween the wire 106 and the electric storage unit 210 in the dischargedirection, the OR circuit 1282 outputs H logic. In another embodiment,if the terminal voltage of the switching unit 230 stays in a particularnumerical range, and if the voltage or SOC of the electric storage unit210 is lower than the threshold for the protection against overcharge,the OR circuit 1282 outputs H logic.

In the present embodiment, the OR circuit 1284 has two input terminalsand one output terminal. To one of the input terminals of the OR circuit1284, the output of the current monitoring unit 1120 is input. To theother input terminal of the OR circuit 1284, the output of the ANDcircuit 1274 is input.

The OR circuit 1284 outputs logical sum (OR) of the two inputs. Forexample, if the output of the OR circuit 1284 is H logic, the transistor520 is turned on, and if the output of the OR circuit 1284 is L logic,the transistor 520 is turned off. In an embodiment, if the current flowsbetween the wire 106 and the electric storage unit 210 in the chargedirection, the OR circuit 1284 outputs H logic. In another embodiment,if the terminal voltage of the switching unit 230 stays in a particularnumerical range, and if the voltage or SOC of the electric storage unit210 is lower than the threshold for the protection against overcharge,the OR circuit 1284 outputs H logic.

Specific Examples of the Operation of the Signal Generating Unit 330

In an embodiment, if the determining unit 310 has decided that thevoltage or SOC of the electric storage unit 210 matches the firstcondition, the signal generating unit 330, for example, outputs to thetransistor 510 a signal for executing the operation for electricallydisconnecting the wire 106 and the electric storage unit 210 or theoperation for reducing the current flowing between the wire 106 and theelectric storage unit 210 in the charge direction. Note that the signalgenerating unit 330 may output a signal to the transistor 520, dependingon the content of the first condition.

In another embodiment, if the determining unit 310 has decided that thevoltage or SOC of the electric storage unit 210 matches the secondcondition, the signal generating unit 330 outputs, for example, to thetransistor 520 a signal for executing the operation for electricallydisconnecting the wire 106 and the electric storage unit 210 or theoperation for reducing the current flowing between the wire 106 and theelectric storage unit 210 in the discharge direction. Note that thesignal generating unit 330 may output a signal to the transistor 510,depending on the content of the second condition.

In still another embodiment, if the determining unit 310 has decidedthat the terminal voltage of the switching unit 230 matches the thirdcondition, the signal generating unit 330 outputs to the transistor 510and the transistor 520 a signal for executing the operation forelectrically connecting the wire 106 and the electric storage unit 210or the operation for increasing the current flowing between the wire 106and the electric storage unit 210, regardless of whether or not thevoltage or SOC of the electric storage unit 210 matches the firstcondition and the second condition. On the other hand, if thedetermining unit 310 has decided that the terminal voltage of theswitching unit 230 does not match the third condition, the signalgenerating unit 330 may output a signal corresponding to the detectionresult of the current monitoring unit 1120. For example, the signalgenerating unit 330 outputs a signal as follows.

[In the case in which (a) the determining unit 310 has decided that theterminal voltage of the switching unit 230 does not match the thirdcondition, and (b) the current monitoring unit 1120 has detected (i) thecurrent flowing between the wire 106 and the electric storage unit 210in the discharge direction when the function of protection againstovercharge is enabled or (ii) the current flowing between the wire 106and the electric storage unit 210 when the transistor 510 electricallydisconnects the wire 106 and the electric storage unit.]

In this case, the signal generating unit 330 outputs to the transistor510 a signal for executing the operation for electrically connecting thewire 106 and the electric storage unit 210 or the operation forincreasing the current flowing between the wire 106 and the electricstorage unit 210, regardless of whether or not the voltage or SOC of theelectric storage unit 210 matches the first condition.

[In the case in which (a) the determining unit 310 has decided that theterminal voltage of the switching unit 230 does not match the thirdcondition, and (c) the current monitoring unit 1120 has detected (i) thecurrent flowing between the wire 106 and the electric storage unit 210in the charge direction when the function of protection against overdischarge is enabled or (ii) the current flowing between the wire 106and the electric storage unit 210 when the transistor 520 electricallydisconnects the wire 106 and the electric storage unit.]

In this case, the signal generating unit 330 outputs to the transistor520 a signal for executing the operation for electrically connecting thewire 106 and the electric storage unit 210 or the operation forincreasing the current flowing between the wire 106 and the electricstorage unit 210, regardless of whether or not the voltage or SOC of theelectric storage unit 210 matches the second condition.

In still another embodiment, the module control unit 1040 can suppressdeterioration or damage of the electric storage unit 210 due to theovercurrent. As described above, if the terminal voltage of theswitching unit 230 is higher than the particular value, which is as anexample in which the switching unit 230 matches the above describedfourth condition, the OR circuit 1260 outputs H logic.

Because of this, if the current flows between the wire 106 and theelectric storage unit 210 in the discharge direction and if the terminalvoltage of the switching unit 230 is higher than the particular value,the L logic is output from the OR circuit 1282. As a result, thetransistor 510 is turned off. Similarly, if the current flows betweenthe wire 106 and the electric storage unit 210 in the charge direction,and if the terminal voltage of the switching unit 230 is higher than theparticular value, L logic is output from the OR circuit 1284. As aresult, the transistor 520 is turned off.

According to the present embodiment, the constant flow of the currentinto the parasitic diode 842 and the parasitic diode 844 can besuppressed. As a result, the terminal voltage of the switching unit 230and the current flowing via the transistor 510 and the transistor 520can be regarded as proportional to each other. Here, the determiningunit 310 and the signal generating unit 330 can be used as theovercurrent protection circuit by appropriately setting the resistancevalue of the current detecting element 1020 and by connecting in serieswith the current detecting element 1020 the resistor having anappropriate resistance value between the wire 106 and the electricstorage unit 210.

FIG. 13 schematically shows an example of the circuit configuration ofthe module control unit 1040. The module control unit 1040 disclosed inFIG. 13 differs from the module control unit 1040 described inassociation with FIG. 12 in that the module control unit 1040 includes aresistor 1310 between the current detecting element 1020 and theelectric storage unit 210. With respect to the configuration other thanthe above described difference, the module control unit 1040 disclosedin FIG. 13 may have the features similar to those of the correspondingconfiguration of the module control unit 1040 described in associationwith FIG. 12.

As described above, the determining unit 310 and the signal generatingunit 330 can be used as the overcurrent protection circuit byappropriately setting the resistance value of the resistor 1310. Theresistance value of the resistor 1310 is decided, for example, such thatthe determining unit 310 can certainly determine whether or not thevalue of the load current stays within a predetermined numerical range.Also, the resistor 1310 may be used as the current detecting elementinstead of the current detecting element 1020. In this case, theelectric storage module 1010 may not include the current detectingelement 1020.

FIG. 14 schematically shows an example of the system configuration of anelectric storage module 1410. In the present embodiment, the electricstorage module 1410 includes a voltage adjusting unit 1430 and differsfrom the electric storage module 1010 in that the module control unit1040 controls the operation of the voltage adjusting unit 1430. Withrespect to the configuration other than the above described difference,the electric storage module 1410 may have the features similar to thoseof the corresponding configuration of the electric storage module 1010.The voltage adjusting unit 1430 may be an example of a first switchingelement and a second switching element.

FIG. 15 schematically shows an example of the circuit configuration ofthe voltage adjusting unit 1430. Also, FIG. 15 schematically shows anexample of the circuit configuration of the module control unit 1040 ofthe electric storage module 1410.

In the present embodiment, the voltage adjusting unit 1430 includes atransistor 1522 and a resistor 1524. In the present embodiment, thevoltage adjusting unit 1430 includes a transistor 1542 and a resistor1544. The transistor 1522 may be an example of the first switchingelement. The transistor 1542 may be an example of the second switchingelement.

In the present embodiment, the module control unit 1040 of the electricstorage module 1410 differs from the module control unit 1040 of theelectric storage module 1010 in that the signal generating unit 330 (notshown in the drawing) includes an AND circuit 1552 and an AND circuit1554. With respect to the configuration other than the above describeddifferences, the module control unit 1040 of the electric storage module1410 may have the features similar to those of the correspondingconfiguration of the module control unit 1040 of the electric storagemodule 1010.

In the present embodiment, between the wire 106 and the electric storageunit 210, the transistor 1522 is connected in parallel with theswitching unit 230. For example, one end of the transistor 1522 iselectrically connected to one end of the switching unit 230. One end ofthe transistor 1522 may be electrically connected to the wire 106 viathe positive terminal 112. On the other hand, the other end of thetransistor 1522 is electrically connected to the other end of theswitching unit 230. The other end of the transistor 1522 may beelectrically connected to the electric storage unit 210.

According to the present embodiment, the electric storage module caneasily be hot-swapped. However, for example, if the electric storagesystem 100 is an apparatus whose frequency of usage is low such as anemergency power supply, after part of the plurality of electric storagemodules included the electric storage system 100 is(are) replaced, itmay take time until the replaced electric storage module(s) is(are)electrically connected to the wire 106 of the electric storage system100. Even in such a case, the transistor 1522 can electrically connectthe wire 106 and the electric storage unit 210 of the electric storagemodule 1410 at an optional timing.

In the present embodiment, the resistor 1524 decides the magnitude ofthe current flowing through the transistor 1522 when the transistor 1522is turned on. The resistance value of the resistor 1524 is decided suchthat an excessive current does not flow through the transistor 1522 whenthe transistor 1522 is turned on. In an embodiment, the resistance valueof the resistor 1524 is decided such that the resistance value of thepath that electrically connects the wire 106 and the electric storageunit 210 via the transistor 1522 becomes higher than the resistancevalue of the path that electrically connects the wire 106 and theelectric storage unit 210 via the switching unit 230.

In another embodiment, the resistance value of the resistor 1524 may bedecided based on ‘the time required to charge the electric storage unit210 from the first SOC to the second SOC at a particular chargingvoltage when the transistor 1522 is turned on. For example, the firstSOC is 25%, and the second SOC is 75%. The first SOC may be 20%, and thesecond SOC may be 80%. Also, the first SOC may be 10%, and the secondSOC may be 90%. The first SOC may be 0%, and the second SOC may be 100%.Examples of the above described time include 12 hours, 18 hours, 24hours, 36 hours, 48 hours, 72 hours, 1 week, 10 days, 15 days, 1 month,2 months, 3 months, and 6 months.

In the present embodiment, one end of the transistor 1542 iselectrically connected to the positive terminal 212 of the electricstorage unit 210, and the other end thereof is electrically connected tothe negative terminal 214 of the electric storage unit 210 or thereference potential. The electric storage unit 210 can thereby bedischarged at an optional timing. As a result, the transistor 1542 canadjust the difference between the voltage of the wire 106 and thevoltage of the electric storage unit 210 of the electric storage module1410 at an optional timing. For example, even if the electric storagesystem 100 is an apparatus whose frequency of usage is low, the electricstorage module 1410 can electrically connect the wire 106 and theelectric storage unit 210 of the electric storage module 1410 at anoptional timing.

In the present embodiment, the resistor 1544 decides the magnitude ofthe current flowing through the transistor 1542 when the transistor 1542is turned on. The resistance value of the resistor 1544 is decided suchthat an excessive current does not flow through the transistor 1542 whenthe transistor 1542 is turned on. In an embodiment, the resistance valueof the resistor 1544 is decided such that the resistance value of thepath that electrically connects one end and the other end of theelectric storage unit 210 via the transistor 1542 becomes higher thanthe resistance value of the path that electrically connects the wire 106and the electric storage unit 210 via the switching unit 230.

In another embodiment, the resistance value of the resistor 1544 may bedecided based on ‘the time required to discharge the electric storageunit 210 from the first SOC to the second SOC when the transistor 1542is turned on’. For example, the first SOC is 75%, and the second SOC is25%. The first SOC may be 80%, and the second SOC may be 20%. Also, thefirst SOC may be 90%, and the second SOC may be 10%. The first SOC maybe 100%, and the second SOC may be 0%. Examples of the above describedtime include 12 hours, 18 hours, 24 hours, 36 hours, 48 hours, 72 hours,1 week, 10 days, 15 days, 1 month, 2 months, 3 months, and 6 months.

In the present embodiment, the AND circuit 1552 has two input terminalsand one output terminal. To one of the input terminals of the ANDcircuit 1552, a signal produced by inverting the signal 88 for enablingthe function of protection against overcharge is input. To the otherinput terminal of the AND circuit 1552, the output from the L terminalof the determining unit 310 is input. The AND circuit 1552 outputslogical product (AND) of the two inputs. The signal 92 having beenoutput from the AND circuit 1552 is input to the input terminal of thetransistor 1522.

In the present embodiment, the AND circuit 1554 has two input terminalsand one output terminal. To one of the input terminals of the ANDcircuit 1554, a signal produced by inverting the signal 86 for enablingthe function of protection against over discharge is input. To the otherinput terminal of the AND circuit 1554, the output from the H terminalof the determining unit 310 is input. The AND circuit 1554 outputslogical product (AND) of the two inputs. The signal 94 having beenoutput from the AND circuit 1554 is input to the input terminal of thetransistor 1522.

The module control unit 1040 can thereby, for example, control theoperation of the transistor 1522 based on (i) voltage or SOC of theelectric storage unit 210, (ii) the voltage of the wire 106, and (iii)the voltage of the positive terminal 212 of the electric storage unit210. Also, the module control unit 1040 can, for example, control theoperation of the transistor 1542 based on (i) the voltage or SOC of theelectric storage unit 210, (ii) the voltage of the wire 106, and (iii)the voltage of the positive terminal 212 of the electric storage unit210.

FIG. 16 schematically shows an example of the voltage adjusting unit1430. The voltage adjusting unit 1430 disclosed in FIG. 16 differs fromthe voltage adjusting unit 1430 described in association with FIG. 15 inthat the voltage adjusting unit 1430 has a bi-directional DC-DCconverter 1630 instead of the transistor 1522 and the resistor 1544.With respect to the configuration other than the above describeddifference, the voltage adjusting unit 1430 disclosed in FIG. 16 mayhave the features similar to those of the corresponding configuration ofthe voltage adjusting unit 1430 described in association with FIG. 15.

In the present embodiment, the bi-directional DC-DC converter 1630 isconnected in parallel with the switching unit 230 between the wire 106and the electric storage unit 210. For example, one end of thebi-directional DC-DC converter 1630 is electrically connected to one endof the switching unit 230. One end of the bi-directional DC-DC converter1630 may be electrically connected to the wire 106 via the positiveterminal 112. On the other hand, the other end of the bi-directionalDC-DC converter 1630 is electrically connected to the other end of theswitching unit 230. The other end of the bi-directional DC-DC converter1630 may be electrically connected to the electric storage unit 210.

The rated current value of the bi-directional DC-DC converter 1630 maybe lower than the rated current value of the switching unit 230. Thespecification of the bi-directional DC-DC converter 1630 may be decidedbased on ‘the time required to charge the electric storage unit 210 fromthe first SOC to the second SOC when the bi-directional DC-DC converter1630 is actuated’. For example, the first SOC is 25%, and the second SOCis 75%. The first SOC may be 20%, and the second SOC may be 80%. Also,the first SOC may be 10%, and the second SOC may be 90%. The first SOCmay be 0%, and the second SOC may be 100%. Examples of the abovedescribed time include 12 hours, 18 hours, 24 hours, 36 hours, 48 hours,72 hours, 1 week, 10 days, 15 days, 1 month, 2 months, 3 months, and 6months.

The specification of the bi-directional DC-DC converter 1630 may bedecided based on ‘the time required to discharge the electric storageunit 210 from the first SOC to the second SOC when the bi-directionalDC-DC converter 1630 is actuated’. For example, the first SOC is 75%,and the second SOC is 25%. The first SOC may be 80%, and the second SOCmay be 20%. The first SOC may be 90%, and the second SOC may be 10%. Thefirst SOC may be 100%, and the second SOC may be 0%. Examples of theabove described time include 12 hours, 18 hours, 24 hours, 36 hours, 48hours, 72 hours, 1 week, 10 days, 15 days, 1 month, 2 months, 3 months,and 6 months. Examples of the specification of the bi-directional DC-DCconverter 1630 include the rated current value and the rated powervalue.

If a bi-directional DC-DC converter is used in order to be a completealternative to the switching unit 230, a large and expensivebi-directional DC-DC converter is used. However, according to thepresent embodiment, the bi-directional DC-DC converter 1630, forexample, transfers an electrical energy from one electric storage module1410 to another electric storage module 1410 by using the period duringwhich the electric storage system 100 is stopped. Because of this, theability of the bi-directional DC-DC converter 1630 may be significantlylower than in the case in which a bi-directional DC-DC converter is usedin order to be a complete alternative to the switching unit 230.

In the present embodiment, the bi-directional DC-DC converter 1630 maybe controlled by the module control unit 1040. The module control unit1040 controls, for example, the operation of the bi-directional DC-DCconverter 1630 based on (i) the voltage or SOC of the electric storageunit 210, (ii) the voltage of the wire 106, and (iii) the voltage of thepositive terminal 212 of the electric storage unit 210.

According to the present embodiment, the bi-directional DC-DC converter1630 can transfer from the electric storage unit 210 to the wire 106 anelectrical energy at an optional timing. Also, the bi-directional DC-DCconverter 1630 can transfer from the wire 106 to the electric storageunit 210 an electrical energy at an optional timing.

FIG. 17 schematically shows an example of the system configuration of anelectric storage module 1710. In the present embodiment, the electricstorage module 1710 differs from the electric storage module 1410 andthe like in that the module control unit 1040 transmits to theprotecting unit 250 at least one of a reset signal of the protectionagainst over discharge and a reset signal of the protection againstovercharge upon deciding to release at least one of the interlock of theprotection against over discharge and the interlock of the protectionagainst overcharge. Also, the electric storage module 1710 differs fromthe electric storage module 1410 and the like in that the protectingunit 250 releases at least one of the interlock of the protectionagainst over discharge and the interlock of the protection againstovercharge by controlling the switching unit 230 upon receiving thereset signal. With respect to the configuration other than the abovedescribed differences, the electric storage module 1710 may have thefeatures similar to those of the corresponding configuration of theelectric storage module 1410 and the like.

In each embodiment described above, the electric storage system 100 hasbeen described in detail using an example in which the switching unitssuch as the switching unit 230, the switching unit 630, and theswitching unit 730 are arranged inside the electric storage modules suchas the electric storage module 110, the electric storage module 710, theelectric storage module 1010, the electric storage module 1410, and theelectric storage module 1710. However, the electric storage system 100is not limited to each embodiment described above.

In another embodiment, the switching unit may be arranged outside theelectric storage module. For example, the switching unit is arrangedbetween the connection terminal 102 of the electric storage system 100and the positive terminal of each electric storage module. The switchingunit may also be arranged between the connection terminal 104 of theelectric storage system 100 and the negative terminal of each electricstorage module. The above described switching unit arranged inside oroutside each electric storage module is sometimes referred to as aswitching unit corresponding to each electric storage module.

FIG. 18 to FIG. 29 are used to describe an example of a method fordeciding the rated voltage of at least one of the electric storagemodule 110 and the electric storage module 120. The rated voltage of theelectric storage module indicates the voltage at a time when thedischarge amount of an electric storage module which is discharged witha predetermined current value becomes half of the total energy of theelectric storage module. For the above described predetermined currentvalue, for example, the value 0.2 C is used. The rated voltage issometimes referred to as an average voltage.

When the electric storage module has a single electric storage cell, therated voltage of the electric storage module may be indicated as therated voltage of the electric storage cell. When the electric storagemodule has a plurality of electric storage cells connected in series,the rated voltage of the electric storage module (i) may be indicated asthe sum of rated voltage of each of the plurality of electric storagecells or (ii) may be indicated as the product of the rated voltage ofthe single electric storage cell and the series number of the electricstorage cells. The rated voltage of the electric storage cell indicatesthe voltage at a time when the discharge amount of an electric storagecell which is discharged with a predetermined current value becomes halfof the total energy of the electric storage cell. For the abovedescribed predetermined current value, for example, the value 0.2 C isused.

As described above, the electric storage system 100 may be electricallyconnected to a plurality of electric storage modules of different types.The availability or supplied amount of the electric storage module orthe electric storage cell constituting the electric storage module maybe different depending on the type of the electric storage module or theelectric storage cell. The size of the electric storage module may bealso different depending on the type of electric storage module.

For example, adjusting the frequency of replacing the electric storagemodule depending on the availability or supplied amount of the electricstorage module or the electric storage cell can further improve theefficiency of the reuse of the electric storage module, the maintenanceof the electric storage system 100, or the like. However, in theelectric storage system 100 described with reference to FIG. 1 to FIG.17, the electrical connection relationship between the electric storagemodule and the electric storage system 100 is automatically switchedaccording to the voltage of the electric storage module. Thus, it isdifficult to charge or discharge a particular electric storage module atany timing regardless of the voltage condition of another electricstorage module.

Furthermore, as described with reference to FIG. 2, the electric storagemodule 110 includes (i) a single electric storage cell or (ii) aplurality of electric storage cells connected in series, which iselectrically connected to the positive terminal 112 and the negativeterminal 114. In the electric storage module 110, the above describedsingle electric storage cell or plurality of electric storage cells isconnected in series with the positive terminal 112 and the negativeterminal 114. In the electric storage module 110, the number of electricstorage cells connected in series with the positive terminal 112 and thenegative terminal 114 may be adjusted to any number. Thus, even if thebattery systems are the same among the above described one or moreelectric storage cells, a different number of the above describedelectric storage cells among the plurality of electric storage modulesmounted to the electric storage system 100 makes it difficult to chargeor discharge a particular electric storage module at any timing.

Then, the embodiments described with reference to FIG. 18 to FIG. 29provide a method for deciding the rated voltage of the first electricstorage device in the electric storage system to which the firstelectric storage device and the second electric storage device connectedin parallel can be mounted. The above described electric storage systemincludes, for example, at least one of (A) a discharge standby stage,where, after the discharge stage, it standbys for the next dischargestage with the voltage of at least one of the first electric storagedevice and the second electric storage device being equal to apredetermined first threshold value or higher than the first thresholdvalue, and (B) a charge standby stage, where, after the charge stage, itstandbys for the next charge stage with the voltage of at least one ofthe first electric storage device and the second electric storage devicebeing equal to a predetermined second threshold value or lower than thesecond threshold value.

The electric storage system 100 may be an example of the electricstorage system to which the first electric storage device and the secondelectric storage device can be mounted. The electric storage module 110may be an example of one of the first electric storage device and thesecond electric storage device. The electric storage module 120 may bean example of the other of the first electric storage device and thesecond electric storage device.

In the above described method, according to one embodiment, the type ofthe first electric storage device is different from the type of thesecond electric storage device. According to another embodiment, thenumber of the electric storage cells connected in series with thepositive terminal and the negative terminal in the first electricstorage device is different from the number of the electric storagecells connected in series with the positive terminal and the negativeterminal in the second electric storage device. For example, the numberof a plurality of electric storage cells connected in series included inthe first electric storage device is different from the number of aplurality of electric storage cells connected in series included in thesecond electric storage device.

Note that the type of the electric storage device may be distinguishedbased on, for example, (i) the pattern of charge and dischargecharacteristic curve and (ii) the magnitude of dV/dQ in a particularstate, even if the battery systems of the electric storage cells are thesame. The charge and discharge characteristic curve may be a curved lineindicating the output voltage relative to the state of charge (sometimesreferred to as SOC) of the electric storage device, may be a curved lineindicating the output voltage relative to the depth of discharge(sometimes referred to as DOD) of the electric storage device, or may bea curved line indicating the OCV (open circuit voltage).

Here, the discharge depth DOD (%) is defined as 100−SOC (%). V is theoutput voltage of the electric storage device, which is for example theelectric storage module 110 or the electric storage module 120, in theassembled battery, which is for example the electric storage system 100.Q is the integrated value of the current flowing through the electricstorage device (sometimes referred to as an electricity amount).Furthermore, the magnitude of dV/dQ indicates the gradient of the chargeand discharge characteristic curve in the above described particularstate. Examples of the above described particular state include a statewhere the discharge amount of the electric storage device which isdischarged with a predetermined current value becomes half of the totalenergy of the electric storage device.

For example, when the electric storage device is a lithium battery or alithium-ion battery (sometimes referred to as Li storage battery),examples of the type of electric storage device include an LFP-based Listorage battery, a ternary-based Li storage battery, an Mn-based Listorage battery, Co-based Li storage battery, Ni-based Li storagebattery, and the like. For example, the LFP-based Li storage batteryshows the charge and discharge characteristic curve with a relativelyflat pattern. On the other hand, the ternary-based Li storage batteryshows the charge and discharge characteristic curve having a patternwith a relatively steep gradient. Therefore, the dV/dQ of the LFP-basedLi storage battery is generally lower than the dV/dQ of theternary-based Li storage battery.

For a simple description, in the present embodiment, the above describedmethod is described in detail using an example where the electricstorage system 100 includes the electric storage module 110 and theelectric storage module 120. However, the above described method is notlimited to the present embodiment. The above described method may beapplied to the electric storage system including three or more electricstorage devices. For example, the above described method is applied tothe electric storage system 100 including one or more electric storagemodules 110 and one or more electric storage modules 120.

In the above described method, an electric storage module (sometimesreferred to as a main device) for which the utilization rate will bemade higher is first decided among the electric storage module 110 andthe electric storage module 120. The utilization rate is decided basedon, for example, at least one of (i) an accumulated time, which is theaccumulated value of at least one of the discharge time and the chargetime during a predetermined period, (ii) an accumulated power amount,which is the accumulated value of at least one of the discharge amountand the charge amount during the predetermined period, and (iii) anaccumulated number, which is the accumulated value of at least one ofthe number of discharging and the number of charging during thepredetermined period.

Then, the large and small relationship between the rated voltage of theelectric storage module whose utilization rate is decided to be madehigher among the electric storage module 110 and the electric storagemodule 120 and the rated voltage of the other electric storage module isdecided. The above described large and small relationship is decidedbased on, for example, the application of the electric storage system100. For example, the application of the electric storage system 100includes (i) the application such as an uninterruptible power supply,where maintaining a relatively high SOC in the discharge standby stageis important, (ii) the application such as a power buffer device, wheremaintaining a relatively low SOC in the charge standby stage isimportant, and the like.

In one embodiment, the electric storage system 100 is used for theapplication where maintaining a relatively high SOC in the dischargestandby stage is important. In this case, the rated voltage of theelectric storage module whose utilization rate is decided to be madehigher among the electric storage module 110 and the electric storagemodule 120 is decided to be made higher than the rated voltage of theother electric storage module.

In another embodiment, the electric storage system 100 is used for theapplication where maintaining a relatively low SOC in the charge standbystage is important. In this case, the rated voltage of the electricstorage module whose utilization rate is decided to be made higher amongthe electric storage module 110 and the electric storage module 120 isdecided to be made lower than the rated voltage of the other electricstorage module.

Then, the rated voltage of at least one of the electric storage module110 and the electric storage module 120 is decided such that the abovedescribed large and small relationship is achieved. For example, therated voltage of the electric storage module 110 may be adjusted byadjusting the series number of the plurality of electric storage cellsincluded in the electric storage module 110. The rated voltage of theelectric storage module 110 may be manually adjusted or may be adjustedthrough the control by the electric storage system 100 or the electricstorage module 110.

[An Embodiment where the Electric Storage System 100 has a DischargeStandby Stage]

The above described method is described in detail with reference to FIG.18 to FIG. 23 using an example where the utilization rate of theelectric storage module 110 is made higher than the utilization rate ofthe electric storage module 120. In the embodiments of FIG. 18 to FIG.23, the above described method is described in detail using an examplewhere the electric storage system 100 is used for the application inwhich maintaining a relatively high SOC in the discharge standby stageis important.

The summary of the discharge standby stage is described with referenceto FIG. 18. FIG. 19 to FIG. 22 are used to describe in detail theoperation of the electric storage system 100 performed when the electricstorage module 110 is for example the LFP-based Li storage battery andthe electric storage module 120 is for example the ternary-based Listorage battery. Furthermore, FIG. 23 is used to describe in detail themethod for adjusting the rated voltage of the electric storage module110.

FIG. 18 schematically shows an example of the discharge standby stage ofthe electric storage system 100. FIG. 18 shows the voltage variation1800 in each step of the electric storage system 100. In FIG. 18, V_(H)indicates the value of a constant voltage in the discharge standbystage. As shown in FIG. 18, when the electric storage system 100 is usedfor the above described application, the voltage of the electric storagesystem 100 is maintained to be equal to V_(H) or higher than V_(H) inthe constant state (that is, the discharge standby stage) of theelectric storage system 100.

When the electric storage system 100 standbys in the discharge standbystage, a power failure occurring outside the electric storage system 100causes the discharge stage of the electric storage system 100 to beperformed. Examples of the power failure include an instantaneousvoltage drop, an instantaneous power outage, and a power outage. Whenthe power failure is resolved, the discharge stage is stopped. Then,when the charge stage is performed and the voltage of the electricstorage system 100 becomes V_(H), the charge stage is stopped and thedischarge standby stage is started.

Next, FIG. 19 and FIG. 20 are used to describe in detail the dischargingoperation of the electric storage system 100 performed when the ratedvoltage of the electric storage module 110 is higher than the ratedvoltage of the electric storage module 120. Specifically, thedischarging operation of each of the electric storage module 110 and theelectric storage module 120 performed when the electric storage system100 shifts from the discharge standby stage to the discharge stage isdescribed in detail.

FIG. 19 schematically shows an example of the charge and dischargecharacteristic of each electric storage module. In FIG. 19, a curvedline 1910 indicates an example of the charge and dischargecharacteristic of the electric storage module 110. Furthermore, a curvedline 1920 indicates an example of the charge and dischargecharacteristic of the electric storage module 120.

As indicated by the curved line 1910, the voltage of the electricstorage module 110 is V_(SH) when the SOC is 100% (that is, when the DODis 0%). Note that the V_(SH) may be equal to the constant voltage V_(H)of the above described electric storage system 100 or may be higher thanthe constant voltage V_(H). In addition, the voltage of the electricstorage module 110 indicates the rated voltage V_(SR) when the dischargeamount of the electric storage module 110 discharged with 0.2 C becomeshalf of the total energy of the electric storage module 110. At thistime, the discharge amount of electric storage system 100 is indicatedas SR in FIG. 19. Then, when the discharge proceeds and the SOC of theelectric storage module 110 becomes 0% (that is, when the DOD becomes100%), the voltage of the electric storage module 110 becomes V_(SL).

As indicated by the curved line 1920, when the SOC is 100%, the voltageof the electric storage module 120 is V_(LH). In addition, the voltageof the electric storage module 120 indicates the rated voltage V_(LR)when the SOC of the electric storage module 120 is SR. Then, when thedischarge proceeds and the SOC of the electric storage module 120becomes 0%, the voltage of the electric storage module 120 becomesV_(LL).

As shown in FIG. 19, in the present embodiment, the rated voltage V_(SR)of the electric storage module 110 is higher than the rated voltageV_(LR) of the electric storage module 120. Furthermore, the dV/dQ at atime when the voltage of the electric storage module 110 is the ratedvoltage V_(SR) is lower than the dV/dQ at a time when the voltage of theelectric storage module 120 is the rated voltage V_(SL).

According to the present embodiment, the voltage V_(SH) of the electricstorage module 110 at a time when the SOC of the electric storage module110 is 100% is higher than the voltage V_(LH) at a time when the SOC ofthe electric storage module 120 of the electric storage module 120 is100%. The set value for the constant voltage V_(H) in a state of thedischarge standby is not particularly limited, but the constant voltageV_(H) in a state of the discharge standby is set to a value which is,for example, lower than the voltage V_(SH) of the above describedelectric storage module 110 and higher than the voltage V_(LH) of theabove described electric storage module 120.

According to the present embodiment, in the discharge standby stage ofthe electric storage system 100, the electric storage unit 210 of theelectric storage module 110 is assured to be electrically connected tothe electric storage system 100. On the other hand, in the dischargestandby stage of the electric storage system 100, the electric storageunit 210 of the electric storage module 120 is not electricallyconnected to the electric storage system 100 depending on the voltage ofthe electric storage module 120.

For example, when (i) in the discharge standby stage of the electricstorage system 100 the SOCs of the electric storage module 110 and theelectric storage module 120 are 100% and (ii) the absolute value of thedifference between V_(SH) and V_(LH) is higher than the set valuerelated to the switching of the switching unit 230 of the electricstorage module 120, the switching unit 230 of the electric storagemodule 120 is in the OFF state. Thus, the electric storage unit 210 ofthe electric storage module 120 is electrically disconnected from theconnection terminal 102 and the connection terminal 104 of the electricstorage system 100.

In this example, when a power failure occurs outside the electricstorage system 100 and the discharge stage of the electric storagesystem 100 is started, only the electric storage module 110 first startsdischarging. Then, when the discharge of the electric storage module 110proceeds and the voltage of, for example, the electric storage system100 (that is, the voltage of the electric storage module 110) becomesV_(LH), the electric storage unit 210 of the electric storage module 120is electrically connected to the electric storage system 100.

Then, in the present embodiment, the electric storage system 100 outputspower through the discharge of the electric storage module 110 and theelectric storage module 120 until the voltage of the electric storagesystem 100 (that is, the voltage of the electric storage module 110 andthe electric storage module 120) becomes V_(SL). When the dischargefurther proceeds and the voltage of the electric storage system 100becomes lower than V_(SL), the electric storage unit 210 of the electricstorage module 110 is electrically disconnected from the electricstorage system 100. Then, the electric storage system 100 outputs powerthrough the discharge of the electric storage module 120 until thevoltage of the electric storage system 100 (that is, the voltage of theelectric storage module 120) becomes V_(LL).

Next, FIG. 20 is used to describe an example of the discharge stage ofthe electric storage system 100 described with reference to FIG. 19.FIG. 20 schematically shows an example of the variation in the currentvalue of the discharge current of each electric storage module. In FIG.20, the curved line 2010 indicates the variation in the output currentIbat of the electric storage module 110 in the discharge stage of theelectric storage system 100. The curved line 2020 indicates thevariation in the output current Ibat of the electric storage module 120in the discharge stage of the electric storage system 100.

As described with reference to FIG. 19, according to the presentembodiment, when the discharge stage of the electric storage system 100is started, only the electric storage module 110 first supplies power.As the discharge proceeds, the voltage of the electric storage system100 becomes V_(LH) at time T_(LH). At this time, the electric storagemodule 120 is electrically connected to the electric storage system 100.Thus, power is supplied from both the electric storage module 110 andthe electric storage module 120. In the present embodiment, the dV/dQ ofthe electric storage module 110 is lower than the dV/dQ of the electricstorage module 120 at time T_(LH). Therefore, the current value of theoutput current of the electric storage module 110 is higher than thecurrent value of the output current of the electric storage module 120.

As the discharge further proceeds, the voltage of the electric storagesystem 100 becomes V_(CN) at time T_(CN). In this case, the dV/dQ of theelectric storage module 110 and the dV/dQ of the electric storage module120 become approximately the same. Therefore, the current value of theoutput current of the electric storage module 110 and the current valueof the output current of the electric storage module 120 becomeapproximately the same.

As the discharge further proceeds, the voltage of the electric storagesystem 100 becomes V_(SL) at time T_(SL) and the electric storage module110 is electrically disconnected from the electric storage system 100.Then, only the electric storage module 120 supplies power until thevoltage of the electric storage system 100 becomes V_(LL) at timeT_(LL).

As shown in FIG. 19 and FIG. 20, according to the present embodiment,the rated voltage of the electric storage module 110 is higher than therated voltage of the electric storage module 120. Therefore, when theelectric storage system 100 is used for the application wheremaintaining a relatively high SOC in the discharge standby stage isimportant, the period during which the electric storage module 110 iselectrically connected to the electric storage system 100 is longer thanthe period during which the electric storage module 120 is electricallyconnected to the electric storage system 100. As a result, theutilization rate of the electric storage module 110 becomes higher thanthe utilization rate of the electric storage module 120.

Next, FIG. 21 and FIG. 22 are used to describe in detail the dischargingoperation of the electric storage system 100 performed when the ratedvoltage of the electric storage module 110 is lower than the ratedvoltage of the electric storage module 120. Specifically, thedischarging operation of each of the electric storage module 110 and theelectric storage module 120 performed when the electric storage system100 shifts from the discharge standby stage to the discharge stage isdescribed in detail.

FIG. 21 schematically shows an example of the charge and dischargecharacteristic of each electric storage module. In FIG. 21, the curvedline 2110 indicates an example of the charge and dischargecharacteristic of the electric storage module 110. Furthermore, thecurved line 2120 indicates an example of the charge and dischargecharacteristic of the electric storage module 120.

As indicated by the curved line 2110, the voltage of the electricstorage module 110 is V_(SH) when the SOC is 100% (that is, when the DODis 0%). In addition, the voltage of the electric storage module 110indicates the rated voltage V_(SR) when the discharge amount of theelectric storage module 110 discharged with 0.2 C becomes half of thetotal energy of the electric storage module 110. At this time, thedischarge amount of electric storage system 100 is indicated as S_(R) inFIG. 21. Then, when the discharge proceeds and the SOC of the electricstorage module 110 becomes 0% (that is, when the DOD becomes 100%), thevoltage of the electric storage module 110 becomes V_(SL).

As indicated by the curved line 2120, when the SOC is 100%, the voltageof the electric storage module 120 is V_(LH). The voltage of theelectric storage module 120 also indicates the rated voltage V_(LR) whenthe SOC of the electric storage module 120 is S_(R). Then, when thedischarge proceeds and the SOC of the electric storage module 120becomes 0%, the voltage of the electric storage module 120 becomesV_(LL).

As shown in FIG. 21, in the present embodiment, the rated voltage V_(SR)Of the electric storage module 110 is lower than the rated voltageV_(LR) of the electric storage module 120. Furthermore, the dV/dQ at atime when the voltage of the electric storage module 110 is the ratedvoltage V_(SR) is lower than the dV/dQ at a time when the voltage of theelectric storage module 120 is the rated voltage V_(LR).

According to the present embodiment, the voltage V_(SH) of the electricstorage module 110 at a time when the SOC of the electric storage module110 is 100% is lower than the voltage V_(LH) at a time when the SOC ofthe electric storage module 120 of the electric storage module 120 being100%. The set value for the constant voltage V_(H) in a state of thedischarge standby is not particularly limited, but the constant voltageV_(H) in a state of the discharge standby is set to a value which is,for example, higher than the voltage V_(SH) of the above describedelectric storage module 110 and lower than the voltage V_(LH) of theabove described electric storage module 120.

According to the present embodiment, in the discharge standby stage ofthe electric storage system 100, the electric storage unit 210 of theelectric storage module 120 is assured to be electrically connected tothe electric storage system 100. On the other hand, in the dischargestandby stage of the electric storage system 100, the electric storageunit 210 of the electric storage module 110 is not electricallyconnected to the electric storage system 100 depending on the voltage ofthe electric storage module 110.

For example, when (i) in the discharge standby stage of the electricstorage system 100 the SOCs of the electric storage module 110 and theelectric storage module 110 are 100% and (ii) the absolute value of thedifference between V_(SH) and V_(LH) is higher than the set valuerelated to the switching of the switching unit 230 of the electricstorage module 110, the switching unit 230 of the electric storagemodule 120 is in the OFF state. Thus, the electric storage unit 210 ofthe electric storage module 110 is electrically disconnected from theconnection terminal 102 and the connection terminal 104 of the electricstorage system 100.

In this example, when a power failure occurs outside the electricstorage system 100 and the discharge stage of the electric storagesystem 100 is started, only the electric storage module 120 first startsdischarging. Then, as the discharge of the electric storage module 120proceeds, and the voltage of, for example, the electric storage system100 (that is, the voltage of the electric storage module 120) becomesV_(SH), the electric storage unit 210 of the electric storage module 110is electrically connected to the electric storage system 100.

Then, in the present embodiment, the electric storage system 100 outputspower through the discharge of the electric storage module 110 and theelectric storage module 120 until the voltage of the electric storagesystem 100 (that is, the voltage of the electric storage module 110 andthe electric storage module 120) becomes V_(SL). When the dischargefurther proceeds and the voltage of the electric storage system 100becomes lower than V_(SL), the electric storage unit 210 of the electricstorage module 110 is electrically disconnected from the electricstorage system 100. Then, the electric storage system 100 outputs powerthrough the discharge of the electric storage module 120 until thevoltage of the electric storage system 100 (that is, the voltage of theelectric storage module 120) becomes V_(LL).

Next, FIG. 22 is used to describe an example of the discharge stage ofthe electric storage system 100 described with reference to FIG. 21.FIG. 22 schematically shows an example of the variation in the currentvalue of the discharge current of each electric storage module. In FIG.22, the curved line 2210 indicates the variation in the output currentIbat of the electric storage module 110 in the discharge stage of theelectric storage system 100. The curved line 2220 indicates thevariation in the output current Ibat of the electric storage module 120in the discharge stage of the electric storage system 100.

As described with reference to FIG. 21, according to the presentembodiment, when the discharge stage of the electric storage system 100is started, only the electric storage module 120 first supplies power.As the discharge proceeds, the voltage of the electric storage system100 becomes V_(SH) at time T_(SH). At this time, the electric storagemodule 110 is electrically connected to the electric storage system 100.Thus, power is supplied from both the electric storage module 110 andthe electric storage module 120. In the present embodiment, at timeT_(SH), the dV/dQ of the electric storage module 120 is lower than thedV/dQ of the electric storage module 110. Therefore, the current valueof the output current of the electric storage module 120 is higher thanthe current value of the output current of the electric storage module110.

As the discharge further proceeds, the voltage of the electric storagesystem 100 becomes V_(CNP) at time T_(CNP). In this case, the dV/dQ ofthe electric storage module 110 and the dV/dQ of the electric storagemodule 120 become approximately the same. Therefore, the current valueof the output current of the electric storage module 110 and the currentvalue of the output current of the electric storage module 120 becomeapproximately the same. Then, the dV/dQ of the electric storage module110 remains lower than the dV/dQ of the electric storage module 120until the voltage of the electric storage system 100 becomes V_(CNS) attime T_(CNS). Therefore, the current value of the output current of theelectric storage module 110 remains higher than the current value of theoutput current of the electric storage module 120.

In the present embodiment, when the voltage of the electric storagesystem 100 becomes V_(CNS), the dV/dQ of the electric storage module 110and the dV/dQ of the electric storage module 120 become approximatelythe same. Therefore, the current value of the output current of theelectric storage module 110 and the current value of the output currentof the electric storage module 120 become approximately the same.

Then, as the discharge further proceeds, the voltage of the electricstorage system 100 becomes V_(SL) at time T_(SL) and the electricstorage module 110 is electrically disconnected from the electricstorage system 100. Then, only the electric storage module 120 suppliespower until the voltage of the electric storage system 100 becomesV_(LL) at time T_(LL).

As shown in FIG. 21 and FIG. 22, according to the present embodiment,the rated voltage of the electric storage module 110 is lower than therated voltage of the electric storage module 120. Therefore, when theelectric storage system 100 is used for the application wheremaintaining a relatively high SOC in the discharge standby stage isimportant, the period during which the electric storage module 110 iselectrically connected to the electric storage system 100 is shorterthan the period during which the electric storage module 120 iselectrically connected to the electric storage system 100. As a result,the utilization rate of the electric storage module 110 becomes lowerthan the utilization rate of the electric storage module 120.

As shown in FIG. 19 to FIG. 22, when the electric storage system 100 isused for the application in which maintaining a relatively high SOC inthe discharge standby stage is important, the rated voltage of theelectric storage module 110 higher than the rated voltage of theelectric storage module 120 can result in the utilization rate of theelectric storage module 110 higher than the utilization rate of theelectric storage module 120. On the other hand, the rated voltage of theelectric storage module 110 lower than the rated voltage of the electricstorage module 120 can result in the utilization rate of the electricstorage module 110 lower than the utilization rate of the electricstorage module 120.

In particular, when the electric storage system 100 is used as anuninterruptible power supply, the electric storage system 100 in aparticular charged state is discharged by any discharge capacity andthen returned to the particular charged state. Thus, the electricstorage system 100 is repeatedly used in a region where the depth ofdischarge is relatively shallow. In this case, since the electricstorage module 110 is mainly used, the deterioration of the electricstorage module 110 is facilitated in comparison with the electricstorage module 120.

The above described method is particularly effective when the charge anddischarge characteristic curve of the electric storage module 110 has arelatively flat pattern. The method for deciding the rated voltage of atleast one of the electric storage module 110 and the electric storagemodule 120 is described below in detail. In addition, examples of themethod for adjusting the rated voltage of the electric storage module110 include, for example, (i) the method for adjusting the rated voltageof each of one or more electric storage cells constituting the electricstorage unit 210, (ii) the method for adjusting the number of electricstorage cells which are electrically connected to the positive terminal212 and the negative terminal 214 among one or more electric storagecells constituting the electric storage unit 210, and the like.

FIG. 23 schematically shows an example of a method for deciding therated voltage of the electric storage module. In the present embodiment,for a simple description, the method for deciding the rated voltage isdescribed in detail using an example in which the rated voltage of theelectric storage module 110 is decided. Note that in another embodimenta similar procedure may be used for deciding the rated voltage of theelectric storage module 120 and for deciding the rated voltage of theelectric storage module 110 and the electric storage module 120.

According to the present embodiment, an electric storage module which ismainly operated is first decided among the electric storage module 110and the electric storage module 120 in S2312. Specifically, which of theelectric storage module 110 and the electric storage module 120 willhave a higher utilization rate is decided. In the present embodiment,the utilization rate of the electric storage module 110 is decided to bemade higher.

Then, the large and small relationship of the rated voltage between theelectric storage module 110 and the electric storage module 120 isdecided in S2314. Specifically, the large and small relationship betweenthe rated voltage of the electric storage module whose utilization rateis decided to be made higher among the electric storage module 110 andthe electric storage module 120 and the rated voltage of the otherelectric storage module is decided.

More specifically, in the embodiment described with reference to FIG. 19to FIG. 22, the electric storage system 100 is used for the applicationwhere maintaining a relatively high SOC in the discharge standby stageis important. In this case, the rated voltage V_(SR) of the electricstorage module 110 whose utilization rate is decided to be made higheramong the electric storage module 110 and the electric storage module120 is decided to be made higher than the rated voltage V_(LR) of theelectric storage module 120.

Then, in S2314, the rated voltage of at least one of the electricstorage module 110 and the electric storage module 120 is decided suchthat the large and small relationship decided in S2316 is achieved. Forexample, in S2314, if the rated voltage V_(SR) of the electric storagemodule 110 is decided to be made higher than the rated voltage V_(LR) ofthe electric storage module 120, the rated voltage V_(SR) of theelectric storage module 110 is decided such that the rated voltageV_(SR) of the electric storage module 110 is equal to the constantvoltage V_(H) in the discharge standby stage of the electric storagesystem 100 or is lower than the constant voltage V_(H).

When the electric storage module 110 is configured such that the seriesnumber of one or more electric storage cells included in the electricstorage unit 210 can be adjusted, the rated voltage V_(SR) of theelectric storage module 110 may be decided based on the above describedseries number which can be adjusted. For example, a case is assumedwhere the electric storage unit 210 of the electric storage module 110includes two hundred electric storage cells connected in series and therated voltage of each electric storage cell is 3.7 V. In addition, acase is assumed where the electric storage module 110 is configured suchthat the number of electric storage cells which can be electricallyconnected to the positive terminal 212 and the negative terminal 214 canbe adjusted. The number is sometimes simply referred to as a seriesnumber of the electric storage cell. Note that the number may bereferred to as the series number of the electric storage cell forconvenience even if the number of the electric storage cell electricallyconnected to the positive terminal 212 and the negative terminal 214 isone.

For example, the electric storage module 110 is configured such that theseries number of the electric storage cell electrically connected to thepositive terminal 212 and the negative terminal 214 can be selected from100, 150, and 200. In this case, the rated voltage of the electricstorage module 110 may be selected from 3.7*100 [V], 3.7*150 [V], and3.7*200 [V].

Then, in S2318, the rated voltage of at least one of the electricstorage module 110 and the electric storage module 120 is adjusted. Forexample, when the rated voltage V_(SR) of the electric storage module110 is to be adjusted, the rated voltage V_(SR) of the electric storagemodule 110 may adjusted by adjusting the series number of one or moreelectric storage cells included in the electric storage module 110. Theseries number of the electric storage cell may be changed before theelectric storage module 110 is mounted to the electric storage system100 or may be changed after the electric storage module 110 is mountedto the electric storage system 100.

In one embodiment, the series number of the electric storage cell ismanually changed when the electric storage module 110 is assembled.Thus, the series number of the electric storage cell is changed beforethe electric storage module 110 is mounted to the electric storagesystem 100.

In another embodiment, the series number of the electric storage cell ischanged through the operation of the circuit incorporated to theelectric storage module 110. Thus, the series number of the electricstorage cell may be changed at any timing. The operation of the abovedescribed circuit may be manually controlled or may be controlledthrough the control signal from the system control unit 140 or themodule control unit 240. For example, the system control unit 140 or themodule control unit 240 outputs the control signal for changing theseries number of the electric storage cells included in the electricstorage system 100.

Note that, as described below, the application of the electric storagesystem 100 is not limited to the application where maintaining arelatively high SOC in the discharge standby stage is important. Whenthe electric storage system 100 is used for another application, thelarge and small relationship between the rated voltage of the electricstorage module whose utilization rate is decided to be made higher andthe rated voltage of the other electric storage module may be decided inan aspect different from that of the present embodiment. In addition,the rated voltage V_(SR) of the electric storage module 110 may bedecided in an aspect different from that of the present embodiment.

For example, when the electric storage system 100 is used for theapplication where maintaining a relatively low SOC in the charge standbystage is important, the rated voltage of the electric storage modulewhose utilization rate is decided to be made higher among the electricstorage module 110 and the electric storage module 120 is decided to bemade lower than the rated voltage of the other electric storage modulein S2314. In addition, in S2316, the rated voltage V_(SR) of theelectric storage module 110 is decided such that the rated voltageV_(SR) of the electric storage module 110 is equal to the constantvoltage in the charge standby stage of the electric storage system 100or higher than the constant voltage.

[An Embodiment in which the Electric Storage System 100 has a ChargeStandby Stage]

In the embodiment of FIG. 19 to FIG. 23, an example of a method foradjusting the utilization rate of the electric storage module 110 andthe electric storage module 120 by adjusting the rated voltage of atleast one of the electric storage module 110 and the electric storagemodule 120 has been described using an example where the electricstorage system 100 is used for the application where maintaining arelatively high SOC in the discharge standby stage is important.However, the method for deciding the rated voltage of the electricstorage module 110 and the electric storage module 120 and the methodfor adjusting the utilization rate of the electric storage module 110and the electric storage module 120 are not limited to the abovedescribed embodiment. In another embodiment, when the electric storagesystem 100 is used for the application where maintaining a relativelylow SOC in the charge standby stage is important, the utilization rateof the electric storage module 110 and the electric storage module 120can be adjusted by adjusting the rated voltage of at least one of theelectric storage module 110 and the electric storage module 120.

FIG. 24 schematically shows an example of a charge standby stage of theelectric storage system 100. FIG. 24 shows a voltage variation 2400 ineach step of the electric storage system 100. In FIG. 24, V_(L)indicates a value of a constant voltage in the charge standby stage. Asshown in FIG. 24, the voltage of the electric storage system 100 in theconstant state, that is, the charge standby stage, is maintained to beequal to V_(L) or lower than V_(L).

When an excess of power occurs outside the electric storage system 100,a charge stage of the electric storage system 100 is performed. Then,when the excess of power is resolved, the charge stage is stopped. Then,when the discharge stage is performed and the voltage of the electricstorage system 100 becomes V_(L), the discharge stage is stopped and thecharge standby stage is started.

Next, FIG. 25 is used to describe an example of the charge stage of theelectric storage system 100 described with reference to FIG. 19. FIG. 25schematically shows an example of the variation in the current value ofthe charge current of each electric storage module. In the presentembodiment, each of the electric storage module 110 and the electricstorage module 120 has a charge and discharge characteristic describedwith reference to FIG. 19.

In FIG. 25, the curved line 2510 indicates the variation in the outputcurrent Ibat of the electric storage module 110 in the charge stage ofthe electric storage system 100. The curved line 2520 indicates thevariation in the output current Ibat of the electric storage module 120in the charge stage of the electric storage system 100. Note that, inFIG. 25, when each electric storage module is being charged, the valueof the output current Ibat is negative.

As described with reference to FIG. 19, according to the presentembodiment, the rated voltage V_(SR) of the electric storage module 110is higher than the rated voltage V_(LR) of the electric storage module120. In addition, the voltage V_(SL) of the electric storage module 110at a time when the SOC of the electric storage module 110 is 0% ishigher than the voltage V_(LL) of the electric storage module 120 at atime when the SOC of the electric storage module 120 is 0%. The constantvoltage V_(L) in a charge standby state is, for example, set to a valuehigher than the voltage V_(LL) of the above described electric storagemodule 120 and lower than voltage V_(SL) of the above described electricstorage module 110, although the set value of the constant voltage V_(L)in a charge standby state is not particularly limited.

According to the present embodiment, the electric storage unit 210 ofthe electric storage module 120 is assured to be electrically connectedto the electric storage system 100 in the charge standby stage of theelectric storage system 100. On the other hand, in the charge standbystage of the electric storage system 100, the electric storage unit 210of the electric storage module 110 is not electrically connected to theelectric storage system 100 depending on the voltage of the electricstorage module 110.

For example, when (i) in the charge standby stage of the electricstorage system 100 the SOCs of the electric storage module 110 and theelectric storage module 120 are approximately 0% and (ii) the absolutevalue of the difference between V_(SL) and V_(LL) is higher than the setvalue related to the switching of the switching unit 230 of the electricstorage module 110, the switching unit 230 of the electric storagemodule 110 is in the OFF state. Thus, the electric storage unit 210 ofthe electric storage module 110 is electrically disconnected from theconnection terminal 102 and the connection terminal 104 of the electricstorage system 100.

In this case, when an excess of power occurs outside the electricstorage system 100 and the charge stage of the electric storage system100 is started, the charge of the electric storage module 120 is firststarted as shown in FIG. 25. At this time, the electric storage module110 is not electrically connected to the electric storage system 100.After that, when the charge proceeds and the voltage of the electricstorage system 100 becomes V_(SL) (that is, the voltage of the electricstorage module 120), as indicated as time T_(SL) in FIG. 25, theelectric storage unit 210 of the electric storage module 110 iselectrically connected to the electric storage system 100.

In the present embodiment, both of the electric storage module 110 andthe electric storage module 120 are charged until the voltage of theelectric storage system 100 (that is, the voltage of the electricstorage module 110 and the electric storage module 120) becomes V_(LH)at time T_(LH). Note that, in this period, the magnitude of chargecurrent of each of the electric storage module 110 and the electricstorage module 120 is decided based on the dV/dQ of each of the electricstorage module 110 and the electric storage module 120.

For example, in the present embodiment, (i) the dV/dQ of the electricstorage module 110 is higher than the dV/dQ of the electric storagemodule 120 until the voltage of the electric storage system 100 becomesV_(CN) at time T_(CN), (ii) when the voltage of the electric storagesystem 100 becomes V_(CN), the dV/dQ of the electric storage module 110becomes equal to the dV/dQ of the electric storage module 120, and (iii)after that, the dV/dQ of the electric storage module 110 is lower thanthe dV/dQ of the electric storage module 120 until the voltage of theelectric storage system 100 becomes V_(LH) at time T_(LH). In this case,during a period when the dV/dQ of the electric storage module 110 ishigher than the dV/dQ of the electric storage module 120, the chargecurrent of the electric storage module 110 is lower than the chargecurrent of the electric storage module 120. In addition, during a periodwhen the dV/dQ of the electric storage module 110 is lower than thedV/dQ of the electric storage module 120, the charge current of theelectric storage module 110 is higher than the charge current of theelectric storage module 120.

When the voltage of the electric storage system 100 becomes V_(LH) attime T_(LH), the electric storage unit 210 of the electric storagemodule 120 is electrically disconnected from the electric storage system100. After that, only the electric storage module 110 is charged. Then,when the voltage of the electric storage system 100 becomes V_(SH) attime T_(SH), the charge of the electric storage module 110 also ends. Atthis time, the electric storage unit 210 of the electric storage module110 may be electrically disconnected from the electric storage system100.

In the following, FIG. 26 is used to describe an example of the chargestage of the electric storage system 100 described with reference toFIG. 21. FIG. 26 schematically shows an example of the variation in thecurrent value of the charge current of each electric storage module. Inthe present embodiment, each of the electric storage module 110 and theelectric storage module 120 has a charge and discharge characteristicdescribed with reference to FIG. 21.

In FIG. 26, the curved line 2610 indicates the variation in the outputcurrent Ibat of the electric storage module 110 in the charge stage ofthe electric storage system 100. The curved line 2620 indicates thevariation in the output current Ibat of the electric storage module 120in the charge stage of the electric storage system 100. Note that, inFIG. 26, when each electric storage module is charged, the value of theoutput current Ibat is negative.

As described with reference to FIG. 21, according to the presentembodiment, the rated voltage V_(SR) of the electric storage module 110is lower than the rated voltage V_(LR) of the electric storage module120. In addition, the voltage V_(SL) of the electric storage module 110at a time when the SOC of the electric storage module 110 is 0% ishigher than the voltage V_(LL) of the electric storage module 120 at atime when the SOC of the electric storage module 120 is 0%. The constantvoltage V_(L) in a charge standby state is, for example, set to a valuehigher than the voltage V_(LL) of the above described electric storagemodule 120 and lower than voltage V_(SL) of the above described electricstorage module 110, although the set value of the constant voltage V_(L)in a charge standby state is not particularly limited.

According to the present embodiment, the electric storage unit 210 ofthe electric storage module 120 is assured to be electrically connectedto the electric storage system 100 in the charge standby stage of theelectric storage system 100. On the other hand, in the charge standbystage of the electric storage system 100, the electric storage unit 210of the electric storage module 110 is not electrically connected to theelectric storage system 100 depending on the voltage of the electricstorage module 110.

For example, when (i) in the charge standby stage of the electricstorage system 100 the SOCs of the electric storage module 110 and theelectric storage module 120 are approximately 0% and (ii) the absolutevalue of the difference between V_(SL) and V_(LL) is higher than the setvalue related to the switching of the switching unit 230 of the electricstorage module 110, the switching unit 230 of the electric storagemodule 110 is in the OFF state. Thus, the electric storage unit 210 ofthe electric storage module 110 is electrically disconnected from theconnection terminal 102 and the connection terminal 104 of the electricstorage system 100.

In this case, when an excess of power occurs outside the electricstorage system 100 and the charge stage of the electric storage system100 is started, the charge of the electric storage module 120 is firststarted as shown in FIG. 26. At this time, the electric storage module110 is not electrically connected to the electric storage system 100.After that, when the charge proceeds and the voltage of the electricstorage system 100 becomes V_(SL) (that is, the voltage of the electricstorage module 120), as indicated as time T_(SL) in FIG. 26, theelectric storage unit 210 of the electric storage module 110 iselectrically connected to the electric storage system 100.

In the present embodiment, both of the electric storage module 110 andthe electric storage module 120 are charged until the voltage of theelectric storage system 100 (that is, the voltage of the electricstorage module 110 and the electric storage module 120) becomes V_(SH)at time T_(SH). Note that, in this period, the magnitude of chargecurrent of each of the electric storage module 110 and the electricstorage module 120 is decided based on the dV/dQ of each of the electricstorage module 110 and the electric storage module 120.

According to the present embodiment, after the voltage of the electricstorage system 100 becomes V_(SL) at time T_(SL), the voltage of theelectric storage system 100 becomes V_(CNS) at time T_(CNS). Accordingto the present embodiment, the dV/dQ of the electric storage module 110is higher than the dV/dQ of the electric storage module 120 during theperiod from time T_(SL) to time T_(CNS). Therefore, during the abovedescribed period, the charge current of the electric storage module 110is lower than the charge current of the electric storage module 120.

On the other hand, the dV/dQ of the electric storage module 110 is lowerthan the dV/dQ of the electric storage module 120 during the perioduntil the voltage of the electric storage system 100 becomes V_(CNP) attime T_(CNP) later. Therefore, during the above described period, thecharge current of the electric storage module 110 is higher than thecharge current of the electric storage module 120.

As the charge further proceeds after the voltage of the electric storagesystem 100 exceeds V_(CNP), the dV/dQ of the electric storage module 110becomes higher than the dV/dQ of the electric storage module 120 untilthe voltage of the electric storage system 100 becomes V_(SH) at timeT_(SH). Therefore, during the above described period, the charge currentof the electric storage module 110 becomes lower than the charge currentof the electric storage module 120.

When the voltage of the electric storage system 100 becomes V_(SH) attime T_(SH), the electric storage unit 210 of the electric storagemodule 110 is electrically disconnected from the electric storage system100. After that, only the electric storage module 120 is charged. Then,when the voltage of the electric storage system 100 becomes V_(LH) attime T_(LH), the charge of the electric storage module 120 also ends. Atthis time, the electric storage unit 210 of the electric storage module120 may be electrically disconnected from the electric storage system100.

As shown in FIG. 25 and FIG. 26, when the electric storage system 100 isused for the application in which maintaining a relatively low SOC inthe charge standby stage is important, the rated voltage of the electricstorage module 110 lower than the rated voltage of the electric storagemodule 120 can result in the utilization rate of the electric storagemodule 110 higher than the utilization rate of the electric storagemodule 120. On the other hand, the rated voltage of the electric storagemodule 110 higher than the rated voltage of the electric storage module120 can result in the utilization rate of the electric storage module110 lower than the utilization rate of the electric storage module 120.

In particular, when the electric storage system 100 is used as a powerbuffer device, the electric storage system 100 in a particulardischarged state is charged by any charge capacity and then returned tothe particular discharged state. Thus, the electric storage system 100is repeatedly used in a region where the depth of discharge isrelatively deep. In this case, since the electric storage module 110 ismainly used, the deterioration of the electric storage module 110 isfacilitated in comparison with the electric storage module 120.

According to the embodiment described with reference to FIG. 19 to FIG.24, the electric storage system 100 has been described in detail usingan example where the electric storage system 100 has a discharge standbystage. In addition, according to the embodiment described with referenceto FIG. 25 or FIG. 26, the electric storage system 100 has beendescribed in detail using an example where the electric storage system100 has a charge standby stage. However, the electric storage system 100is not limited to these embodiments.

In another embodiment, the single electric storage system 100 may have adischarge standby stage and the charge standby stage. For example, theelectric storage system 100 is operated such that the SOC of theelectric storage system 100 is a predetermined value when the electricstorage module 110 standbys for discharge or charge (sometimes referredto as a constant state). For example, the electric storage module 110 isoperated such that the SOC is 50% in the constant state.

According to the above described embodiment, a power failure occurringoutside the electric storage system 100 during a period when theelectric storage system 100 standbys in the constant state causes thedischarge stage of the electric storage system 100 to be performed. Onthe other hand, an excess of power occurring outside the electricstorage system 100 during a period when the electric storage system 100standbys in the constant state causes the charge stage of the electricstorage system 100 to be performed. Thus, the electric storage system100 can support both the power failure and the excess of power outsidethe electric storage system 100.

[A Method for Adjusting the Series Number of the Electric Storage Cell]

An example of a method for adjusting the series number of the electricstorage cells is described with reference to FIG. 27, FIG. 28 and FIG.29. An example of the electric storage unit 2710 in which the seriesnumber of the electric storage cell can be adjusted is described withreference to FIG. 27. An example of a method for controlling theelectric storage unit 2710 is described with reference to FIG. 28 andFIG. 29.

FIG. 27 shows an example of the internal structure of an electricstorage unit 2710. Instead of the electric storage unit 210, theelectric storage unit 2710 may be mounted to any electric storage modulesuch as the electric storage module 110, the electric storage module120, the electric storage module 710, the electric storage module 1010,the electric storage module 1410, and the electric storage module 1710.

In the present embodiment, an electric storage unit 2710 includes apositive terminal 2712 and the negative terminal 2714. In the presentembodiment, the electric storage unit 2710 includes a plurality ofelectric storage cells connected in series including an electric storagecell 2722, an electric storage cell 2724, an electric storage cell 2732,and an electric storage cell 2734. In the present embodiment, theelectric storage unit 2710 includes a single pole double throw switch2742 and a single pole double throw switch 2744. In the presentembodiment, the electric storage unit 2710 includes a terminal 2752 anda terminal 2754.

The electric storage unit 2710 is different from the electric storageunit 210 in that it includes the single pole double throw switch 2742and the single pole double throw switch 2744 and has a larger number ofthe electric storage cells. The electric storage unit 2710 may havefeatures similar to those of the electric storage unit 210, regardingthe components except the above described difference. Instead of theelectric storage unit 210, the electric storage unit 2710 is implementedin the electric storage module in, for example, at least one of theabove described plurality of embodiments.

In the present embodiment, the positive terminal 2712 may have featuressimilar to those of the positive terminal 212. In the presentembodiment, the negative terminal 2714 may have features similar tothose of the negative terminal 214. In the present embodiment, each ofthe electric storage cell 2722, the electric storage cell 2724, theelectric storage cell 2732, and the electric storage cell 2734 may havefeatures similar to those of the electric storage cell 222 or theelectric storage cell 224.

In the present embodiment, the single pole double throw switch 2742electrically connects the positive terminal 2712 to any one of thepositive terminal of the electric storage cell 2722 and the positiveterminal of the electric storage cell 2724. Likewise, the single poledouble throw switch 2742 electrically connects the negative terminal2714 to any one of the negative terminal of the electric storage cell2732 and the negative terminal of the electric storage cell 2734. Thus,the number of electric storage cells electrically connected to thepositive terminal 2712 and the negative terminal 2714 among theplurality of electric storage cells connected in series included in theelectric storage system 100 is adjusted.

In one embodiment, at least one of the single pole double throw switch2742 and the single pole double throw switch 2744 may operate based onthe signal from the module control unit 240. In another embodiment, theuser may manually operate at least one of the single pole double throwswitch 2742 and the single pole double throw switch 2744.

In the present embodiment, the terminal 2752 electrically connects theelectric storage cell 2722 and the electric storage cell 2724 to thebalance correcting unit 260. The terminal 2752 may electrically connectthe electric storage cell 2722 and the electric storage cell 2724 to theprotecting unit 250.

In the present embodiment, the terminal 2754 electrically connects theelectric storage cell 2732 and the electric storage cell 2734 to thebalance correcting unit 260. The terminal 2752 may electrically connectthe electric storage cell 2732 and the electric storage cell 2734 to theprotecting unit 250.

Note that, in the present embodiment, when the electric storage unit2710 is mounted to the electric storage module 110, the protecting unit250 may protect each of the plurality of electric storage cells includedin the electric storage unit 2710. The protecting unit 250 may obtainthe information related to the terminal voltage of each of the pluralityof electric storage cells included in the electric storage unit 2710.

Likewise, if the electric storage unit 2710 is mounted to the electricstorage module 110, the electric storage module 110 may include aplurality of balance correcting units 260. As described above, if theelectric storage unit 2710 may have n (n is an integer equal to orlarger than 2) electric storage cells, the electric storage module 110has n−1 balance correcting unit 260.

In the present embodiment, the positive terminal 2712, the negativeterminal 2714, the electric storage cell 2722, the electric storage cell2724, the electric storage cell 2732, the electric storage cell 2734,the single pole double throw switch 2742, the single pole double throwswitch 2744, the terminal 2752, and the terminal 2754 are supported onor accommodated in the same housing. The positive terminal 2712, thenegative terminal 2714, the electric storage cell 2722, the electricstorage cell 2724, the electric storage cell 2732, the electric storagecell 2734, the single pole double throw switch 2742, the single poledouble throw switch 2744, the terminal 2752, and the terminal 2754 maybe supported on or accommodated in the same housing as that of theswitching unit 230 and at least one of the module control unit 240 orthe module control unit 1040.

The positive terminal 2712 may be an example of the first positiveterminal. The negative terminal 2714 may be an example of the secondnegative terminal. The electric storage cell 2722 may be an example ofthe first electric storage cell. The electric storage cell 2724 may bean example of the first electric storage cell. The electric storage cell2732 may be an example of the first electric storage cell. The electricstorage cell 2734 may be an example of the first electric storage cell.The single pole double throw switch 2742 may be an example of theadjusting device. The single pole double throw switch 2744 may be anexample of the adjusting device.

Note that in the present embodiment the electric storage unit 2710 hasbeen described in detail by using an example where the electric storageunit 2710 includes the single pole double throw switch 2742 and thesingle pole double throw switch 2744. However, the electric storage unit2710 is not limited to the present embodiment. In another embodiment,the electric storage unit 2710 may not include one of the single poledouble throw switch 2742 and the single pole double throw switch 2744.In addition, at least one of the single pole double throw switch 2742and the single pole double throw switch 2744 may be any single polemultiple throw switch. For example, the single pole multiple throwswitch which may be used instead of the single pole double throw switch2742 electrically connects the positive terminal 2712 to the positiveterminal of any one of three or more electric storage cells connected inseries. Likewise, the single pole multiple throw switch which may beused instead of the single pole double throw switch 2744 electricallyconnects the negative terminal 2714 to the positive terminal of any oneof three or more electric storage cells connected in series.

FIG. 28 schematically shows another example of the module control unit240. The module control unit 240 described with reference to FIG. 28 isdifferent from the module control unit 240 described with reference toFIG. 3 in that it includes a signal generating unit 2830 instead of thesignal generating unit 330. With respect to the components except theabove described difference, the module control unit 240 described withreference to FIG. 28 may have features similar to those of the modulecontrol unit 240 described with reference to FIG. 3. For example, in thepresent embodiment, the module control unit 240 or each portion thereofmay be achieved with hardware or may be achieved with software.

In the present embodiment, the signal generating unit 2830 furthergenerates a signal to control an operation of at least one of the singlepole double throw switch 2742 and the single pole double throw switch2744. The signal generating unit 2830 may have components similar to thesignal generating unit 330, except the above described operation.

More specifically, the signal generating unit 2830 obtains theinformation indicating the rated voltage of the electric storage module110 from the system control unit 140. For example, the signal generatingunit 2830 obtains the information indicating the series number of theelectric storage cell included in the electric storage module 110. Thesignal generating unit 2830 controls the operation of at least one ofthe single pole double throw switch 2742 and the single pole doublethrow switch 2744 to generate a signal to adjust the series number ofthe electric storage cells included in the electric storage module 110.The signal generating unit 2830 may output the generated signal to atleast one of the single pole double throw switch 2742 and the singlepole double throw switch 2744.

FIG. 29 schematically shows another example of the system control unit140. In the present embodiment, the system control unit 140 includes thestate managing unit 410, the module selecting unit 420, the signalgenerating unit 430, and a rated voltage adjusting unit 2940. In thepresent embodiment, the rated voltage adjusting unit 2940 has a maindevice deciding unit 2950, a large and small relationship deciding unit2960, a rated voltage deciding unit 2970, and a control signal outputunit 2980. In the present embodiment, the large and small relationshipdeciding unit 2960 includes a first large and small relationshipdeciding unit 2962 and a second large and small relationship decidingunit 2964.

The system control unit 140 described with reference to FIG. 29 isdifferent from the system control unit 140 described with reference toFIG. 4 in that it includes the rated voltage adjusting unit 2940. Withrespect to the components except the above described difference, thesystem control unit 140 described with reference to FIG. 29 may havefeatures similar to those of the system control unit 140 described withreference to FIG. 4. For example, in the present embodiment, the systemcontrol unit 140 or each portion thereof may be achieved with hardwareor may be achieved with software.

In the present embodiment, the rated voltage adjusting unit 2940 adjuststhe rated voltage of at least one of the electric storage module 110 andthe electric storage module 120. For example, if the rated voltageadjusting unit 2940 adjusts the rated voltage of the electric storagemodule 110, the rated voltage adjusting unit 2940 controls the electricstorage system 100 or the electric storage module 110 to adjust therated voltage of the electric storage module 110.

In the present embodiment, the main device deciding unit 2950 decides,for example, the electric storage module whose utilization rate is to bemade higher among the electric storage module 110 and the electricstorage module 120. In the present embodiment, the large and smallrelationship deciding unit 2960 decides the large and small relationshipbetween the rated voltage of the electric storage module whoseutilization rate is decided to be made higher by the main devicedeciding unit 2950, for example, among the electric storage module 110and the electric storage module 120, and the rated voltage of the otherelectric storage module.

In the present embodiment, the first large and small relationshipdeciding unit 2962 decides the above described large and smallrelationship, for example, when the electric storage system 100 has adischarge standby stage. Specifically, the first large and smallrelationship deciding unit 2962 decides to make the rated voltage of theelectric storage module whose utilization rate is decided to be madehigher by the main device deciding unit 2950 higher than the ratedvoltage of the other electric storage module.

In the present embodiment, the second large and small relationshipdeciding unit 2964 decides the above described large and smallrelationship, for example, when the electric storage system 100 has thecharge standby stage. Specifically, the first large and smallrelationship deciding unit 2962 decides to make the rated voltage of theelectric storage module whose utilization rate is decided to be madehigher by the main device deciding unit 2950 lower than the ratedvoltage of the other electric storage module.

In the present embodiment, the rated voltage deciding unit 2970 decidesthe rated voltage of at least one of the electric storage module 110 andthe electric storage module 120 such that the large and smallrelationship decided by the large and small relationship deciding unit2960 is achieved. When the series number of the electric storage cellsof the electric storage unit 2710 can be adjusted, the rated voltagedeciding unit 2970 may decide the rated voltage of at least one of theelectric storage module 110 and the electric storage module 120 based onthe series number which can be adjusted.

In one embodiment, for example, if the first large and smallrelationship deciding unit 2962 decides to make the rated voltage of theelectric storage module 110 higher than the rated voltage of theelectric storage module 110, the rated voltage deciding unit 2970decides the rated voltage of the electric storage module 110 such thatthe rated voltage of the electric storage module 110 is equal to theconstant voltage V_(H) in the discharge standby stage of the electricstorage system 100 or lower than the constant voltage V_(H). In anotherembodiment, for example, if the second large and small relationshipdeciding unit 2964 decides to make the rated voltage of the electricstorage module 110 lower than the rated voltage of the electric storagemodule 110, the rated voltage deciding unit 2970 decides the ratedvoltage of the electric storage module 110 such that the rated voltageof the electric storage module 110 is equal to the constant voltageV_(L) in the charge standby stage of the electric storage system 100 orlower than the constant voltage V_(L).

In the present embodiment, the control signal output unit 2980 generatesa signal to adjust the rated voltage of the electric storage unit 2710based on the rated voltage decided by the rated voltage deciding unit2970. For example, the control signal output unit 2980 generates asignal to control the operation of at least one of the single poledouble throw switch 2742 and the single pole double throw switch 2744 ofthe electric storage unit 2710. For example, if the control signaloutput unit 2980 generates a signal to adjust the rated voltage of theelectric storage module 110, the control signal output unit 2980generates a signal including the information indicating the value of therated voltage of the electric storage module 110 or the informationindicating the series number of the electric storage cells in theelectric storage module 110.

In the present embodiment, the control signal output unit 2980 outputsthe above described signal to the module control unit 240. Note that, inanother embodiment, the control signal output unit 2980 may output theabove described signal to, for example, the electric storage module 110.

The rated voltage adjusting unit 2940 may be an example of a ratedvoltage adjusting device. The electric storage module 110 may be anexample of the first electric storage device. The series number whichcan be adjusted may be an example of the number which can be adjusted bythe adjusting device.

In the embodiment described with reference to FIG. 27 to FIG. 29, anexample of a method for adjusting the rated voltage of the electricstorage module 110 has been described by using an example where (i) thesystem control unit 140 of the electric storage system 100 includes therated voltage adjusting unit 2940 which outputs a control signal toadjust the rated voltage of the electric storage module 110 and (ii) themodule control unit 240 of the electric storage module 110 outputs asignal to control the operation of at least one of the single poledouble throw switch 2742 and the single pole double throw switch 2744 ofthe electric storage module 110 based on the control signal obtainedfrom the system control unit 140.

However, the method for adjusting the rated voltage of the electricstorage module 110 is not limited to the above described embodiment. Inanother embodiment, the electric storage module 110 may partially orentirely include the rated voltage adjusting unit 2940.

While the embodiments of the present invention have been described, thetechnical scope of the invention is not limited to the above describedembodiments. It is apparent to persons skilled in the art that variousalterations and improvements can be added to the above-describedembodiments. An item described according to a particular embodiment canbe applied to another embodiment within a range without beingtechnically conflicted. It is also apparent from the scope of the claimsthat the embodiments added with such alterations or improvements can beincluded in the technical scope of the invention.

The operations, procedures, steps, and stages of each process performedby an apparatus, system, program, and method shown in the claims,embodiments, or diagrams can be performed in any order as long as theorder is not indicated by “prior to,” “before,” or the like and as longas the output from a previous process is not used in a later process.Even if the process flow is described using phrases such as “first” or“next” in the claims, embodiments, or diagrams, it does not necessarilymean that the process must be performed in this order.

EXPLANATION OF REFERENCES

12: load device; 14: charging device; 52: signal; 54: signal; 82:signal; 86: signal; 88: signal; 92: signal; 94: signal; 100: electricstorage system; 102: connection terminal; 104: connection terminal; 106:wire; 110: electric storage module; 112: positive terminal; 114:negative terminal; 120: electric storage module; 122: positive terminal;124: negative terminal; 140: system control unit; 210: electric storageunit; 212: positive terminal; 214: negative terminal; 222: electricstorage cell; 224: electric storage cell; 230: switching unit; 240:module control unit; 250: protecting unit; 260: balance correcting unit;310: determining unit; 320: receiving unit; 330: signal generating unit;340: module information acquiring unit; 350: module information storingunit; 360: module information transmitting unit; 410: state managingunit; 420: module selecting unit; 430: signal generating unit; 510:transistor; 512: resistor; 514: resistor; 516: diode; 520: transistor;522: resistor; 524: resistor; 526: diode; 530: transistor; 532:resistor; 540: transistor; 542: resistor; 552: resistor; 554: resistor;560: transistor; 570: capacitor; 572: resistor; 580: transistor; 592:switch; 594: switch; 630: switching unit; 632: relay; 710: electricstorage module; 730: switching unit; 842: parasitic diode; 844:parasitic diode; 852: logic circuit; 854: logic circuit; 900: electricstorage system; 902: diode; 904: diode; 1010: electric storage module;1020: current detecting element; 1040: module control unit; 1120:current monitoring unit; 1122: current detecting unit; 1124: directiondeciding unit; 1260: OR circuit; 1272: AND circuit; 1274: AND circuit;1282: OR circuit; 1284: OR circuit; 1310: resistor; 1410: electricstorage module; 1430: voltage adjusting unit; 1522: transistor; 1524:resistor; 1542: transistor; 1544: resistor; 1552: AND circuit; 1554: ANDcircuit; 1630: bi-directional DC-DC converter; 1710: electric storagemodule; 1800: voltage variation; 1910: curved line; 1920: curved line;2010: curved line; 2020; curved line; 2110: curved line; 2120: curvedline; 2210: curved line; 2220: curved line; 2400: voltage variation;2510: curved line; 2520: curved line; 2610: curved line; 2620: curvedline; 2710: electric storage unit; 2712: positive terminal; 2714:negative terminal; 2722: electric storage cell; 2724: electric storagecell; 2732: electric storage cell; 2734: electric storage cell; 2742:single pole double throw switch; 2744: single pole double throw switch;2752: terminal; 2754: terminal; 2830: signal generating unit; 2940:rated voltage adjusting unit; 2950: main device deciding unit; 2960:large and small relationship deciding unit; 2962: first large and smallrelationship deciding unit; 2964: second large and small relationshipdeciding unit; 2970: rated voltage deciding unit; 2980: control signaloutput unit

What is claimed is:
 1. A method for deciding a rated voltage of a firstelectric storage device, wherein the first electric storage device and asecond electric storage device are connected in parallel and can bemounted to an electric storage system, the electric storage systemhaving at least one of (A) a discharge standby stage, which is performedafter a discharge stage is performed, for standbying for a nextdischarge stage, with a voltage of at least one of the first electricstorage device and the second electric storage device being equal to apredetermined first threshold value or higher than the first thresholdvalue and (B) a charge standby stage, which is performed after a chargestage is performed, for standbying for a next charge stage, with avoltage of at least one of the first electric storage device and thesecond electric storage device being equal to a predetermined secondthreshold value or lower than the second threshold value, wherein a typeof the first electric storage device is different from a type of thesecond electric storage device, or the number of electric storage cellswhich are in the first electric storage device and are connected inseries with a positive terminal and a negative terminal of the firstelectric storage device is different from the number of electric storagecells which are in the second electric storage device and are connectedin series with a positive terminal and a negative terminal of the secondelectric storage device, the method comprising: a main device decidingstep for deciding an electric storage device, among the first electricstorage device and the second electric storage device, for which atleast one of (i) an accumulated time, which is an accumulated value ofat least one of a discharge time and a charge time during apredetermined period, (ii) an accumulated power amount, which is anaccumulated value of at least one of a discharge amount and a chargeamount during the predetermined period, and (iii) an accumulated number,which is an accumulated value of at least one of the number ofdischarging and the number of charging during the predetermined periodis to be made higher; a large and small relationship deciding step fordeciding a large and small relationship between a rated voltage of theelectric storage device, among the first electric storage device and thesecond electric storage device, for which at least one of (i) theaccumulated time, (ii) the accumulated power amount, and (iii) theaccumulated number is decided to be made higher in the main devicedeciding step, and a rated voltage of an other electric storage device;and a rated voltage deciding step for deciding a rated voltage of thefirst electric storage device such that the large and small relationshipdecided in the large and small relationship deciding step is achieved,the large and small relationship deciding step including: (a) a firstlarge and small relationship deciding step, which is performed when theelectric storage system has the discharge standby stage, for deciding tomake the rated voltage of the electric storage device, among the firstelectric storage device and the second electric storage device, forwhich at least one of (i) the accumulated time, (ii) the accumulatedpower amount, and (iii) the accumulated number is decided to be madehigher in the main device deciding step, higher than the rated voltageof the other electric storage device; or (b) a second large and smallrelationship deciding step, which is performed when the electric storagesystem has the charge standby stage, for deciding to make the ratedvoltage of the electric storage device, among the first electric storagedevice and the second electric storage device, for which at least one of(i) the accumulated time, (ii) the accumulated power amount, and (iii)the accumulated number is decided to be made higher in the main devicedeciding step, lower than the rated voltage of the other electricstorage device.
 2. The method according to claim 1, wherein the ratedvoltage deciding step includes deciding the rated voltage of the firstelectric storage device such that, when the rated voltage of the firstelectric storage device is decided to be made higher than the ratedvoltage of the second electric storage device in the first large andsmall relationship deciding step, the rated voltage of the firstelectric storage device is equal to the first threshold value or lowerthan the first threshold value.
 3. The method according to claim 1,wherein the rated voltage deciding step includes deciding the ratedvoltage of the first electric storage device such that, when the ratedvoltage of the first electric storage device is decided to be made lowerthan the rated voltage of the second electric storage device in thesecond large and small relationship deciding step, the rated voltage ofthe first electric storage device is equal to the second threshold valueor higher than the second threshold value.
 4. The method according toclaim 1, wherein the first electric storage device includes: a firstpositive terminal; a first negative terminal; a plurality of firstelectric storage cells connected in series; and an adjusting devicewhich is configured to adjust the number of electric storage cellselectrically connected to the first positive terminal and the firstnegative terminal among the plurality of first electric storage cells,and the rated voltage deciding step includes deciding the rated voltageof the first electric storage device based on the number adjustable bythe adjusting device.
 5. The method according to claim 4, furthercomprising a control signal output step for outputting a signal tocontrol an operation of the adjusting device based on the rated voltageof the first electric storage device which is decided in the ratedvoltage deciding step.
 6. The method according to claim 4, wherein theadjusting device includes one or more single pole multiple throwswitches.
 7. The method according to claim 1, wherein the first electricstorage device is configured to be attachable and detachable to/from theelectric storage system.
 8. The method according to claim 1, wherein themain device deciding step, the large and small relationship decidingstep, and the rated voltage deciding step are executed by a computer. 9.A rated voltage adjusting device configured to adjust a rated voltage ofa first electric storage device by controlling the first electricstorage device or an electric storage system, wherein the first electricstorage device and a second electric storage device are connected inparallel and can be mounted to an electric storage system having atleast one of (A) a discharge standby stage, which is performed after adischarge stage is performed, for standbying for a next discharge stage,with a voltage of at least one of the first electric storage device andthe second electric storage device being equal to a predetermined firstthreshold value or higher than the first threshold value and (B) acharge standby stage, which is performed after a charge stage isperformed, for standbying for a next charge stage, with a voltage of atleast one of the first electric storage device and the second electricstorage device being equal to a predetermined second threshold value orlower than the second threshold value, and the first electric storagedevice is configured to be attachable and detachable to/from theelectric storage system, and a type of the first electric storage deviceis different from a type of the second electric storage device, or thenumber of electric storage cells which are in the first electric storagedevice and are connected in series with a positive terminal and anegative terminal of the first electric storage device is different fromthe number of electric storage cells which are in the second electricstorage device and are connected in series with a positive terminal anda negative terminal of the second electric storage device, the ratedvoltage adjusting device comprising: a main device deciding unit fordeciding an electric storage device, among the first electric storagedevice and the second electric storage device, for which at least one of(i) an accumulated time, which is an accumulated value of at least oneof a discharge time and a charge time during a predetermined period,(ii) an accumulated power amount, which is an accumulated value of atleast one of a discharge amount and a charge amount during thepredetermined period, and (iii) an accumulated number, which is anaccumulated value of at least one of the number of discharging and thenumber of charging during the predetermined period is to be made higher;a large and small relationship deciding unit for deciding a large andsmall relationship between a rated voltage of the electric storagedevice, among the first electric storage device and the second electricstorage device, for which at least one of (i) the accumulated time, (ii)the accumulated power amount, and (iii) the accumulated number isdecided to be made higher in the main device deciding unit, and therated voltage of an other electric storage device; and a rated voltagedeciding unit for deciding the rated voltage of the first electricstorage device such that the large and small relationship decided in thelarge and small relationship deciding unit is achieved, the large andsmall relationship deciding unit including: (a) a first large and smallrelationship deciding unit configured to, when the electric storagesystem has the discharge standby stage, decide to make the rated voltageof the electric storage device, among the first electric storage deviceand the second electric storage device, for which at least one of (i)the accumulated time, (ii) the accumulated power amount, and (iii) theaccumulated number is decided to be made higher by the main devicedeciding unit, higher than the rated voltage of the other electricstorage device; or (b) a second large and small relationship decidingunit configured to, when the electric storage system has the chargestandby stage, decide to make the rated voltage of the electric storagedevice, among the first electric storage device and the second electricstorage device, for which at least one of (i) the accumulated time, (ii)the accumulated power amount, and (iii) the accumulated number isdecided to be made higher in the main device deciding unit, lower thanthe rated voltage of the other electric storage device.
 10. The ratedvoltage adjusting device according to claim 9, wherein the firstelectric storage device includes: a first positive terminal; a firstnegative terminal; a plurality of first electric storage cells connectedin series; and an adjusting device configured to adjust the number ofelectric storage cells electrically connected to the first positiveterminal and the first negative terminal among the plurality of firstelectric storage cells.
 11. The rated voltage adjusting device accordingto claim 10, wherein the rated voltage deciding unit is configured todecide the rated voltage of the first electric storage device based onthe number adjustable by the adjusting device.
 12. The rated voltageadjusting device according to claim 10, further comprising a controlsignal output unit configured to output a signal to control an operationof the adjusting device based on the rated voltage of the first electricstorage device which is decided by the rated voltage deciding unit. 13.The rated voltage adjusting device according to claim 9, wherein therated voltage adjusting device is arranged inside the electric storagesystem or the first electric storage device.
 14. The rated voltageadjusting device according to claim 9, further comprising a controldevice configured to control current flowing between a wire which isarranged to connect the first electric storage device and the secondelectric storage device in parallel to each other, and the firstelectric storage device, wherein the control device includes: aswitching element arranged between the wire and the first electricstorage device; and a control unit configured to control the switchingelement such that (i) when a terminal voltage of the switching elementmeets a predetermined condition, the switching element electricallyconnects the wire to the electric storage cell, and (ii) when theterminal voltage of the switching element does not meet thepredetermined condition, the switching element electrically disconnectsthe wire from the electric storage cell.
 15. An electric storage systemcomprising: a first electric storage device; and a second electricstorage device connected to the first electric storage device inparallel, the second electric storage device having a charge anddischarge characteristic curve of different pattern from the firstelectric storage device, wherein the electric storage system isconfigured to perform at least one of a discharge standby stage and acharge standby stage, the discharge standby stage being performed aftera discharge stage of the electric storage system, to charge the electricstorage system and maintain a voltage of the electric storage system ata predetermined constant voltage for standbying for a next dischargestage, and the charge standby stage being performed after a charge stageof the electric storage system, to discharge the electric storage systemand maintain the voltage of the electric storage system at anotherpredetermined constant voltage for standbying for a next charge stage,the first electric storage device has a gradient of variation in anoutput voltage with respect to a state of charge different from thesecond electric storage device; and the electric storage systemincludes: (1) if the electric storage system is configured to performthe discharge standby stage, a first discharge mode in which thedischarge is started from the constant voltage for the discharge standbystage higher than any of the rated voltages of the first electricstorage device and the second electric storage device, and a seconddischarge mode in which the discharge is started from the constantvoltage for the discharge standby stage between the rated voltage of thefirst electric storage device and the rated voltage of the secondelectric storage device; and (2) if the electric storage system isconfigure to perform the charge standby stage, a first charge mode inwhich the charge is started from the constant voltage for the chargestandby stage lower than any of the rated voltages of the first electricstorage device and the second electric storage device, and a secondcharge mode in which the charge is started from the constant voltage forthe charge standby stage between the rated voltage of the first electricstorage device and the rated voltage of the second electric storagedevice.
 16. The electric storage system according to claim 15, whereinthe first electric storage device has the gradient of variation in anoutput voltage smaller than the second electric storage device, at astate of charge which defines the rated voltage of the first electricstorage device.
 17. The electric storage system according to claim 16,wherein the first electric storage device has the rated voltage higherthan the second electric storage device.
 18. The electric storage systemaccording to claim 16, wherein the first electric storage device has therated voltage lower than the second electric storage device.
 19. Theelectric storage system according to claim 15, further configured toperform the discharge standby stage, and to switch the constant voltagebetween the first discharge mode and the second discharge mode.
 20. Theelectric storage system according to claim 15, further configured toperform the charge standby stage, and to switch the constant voltagebetween the first charge mode and the second charge mode.